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Sample records for deflecting mode cavity

  1. High Power Test Of A 3.9 GHz 5-cell Deflecting-mode Cavity In A Cryogenic Operation

    CERN Document Server

    Shin, Young-Min

    2014-01-01

    A 3.9 GHz deflecting mode (pi, TM110) cavity has been long used for six-dimensional phase-space beam manipulation tests at the A0 Photo-Injector Lab (16 MeV) in Fermilab and their extended applications with vacuum cryomodules are currently planned at the Advanced Superconducting Test Accelerator (ASTA) user facility (> 50 MeV). Despite the successful test results, the cavity, however, demonstrated limited RF performance during liquid nitrogen (LN2) ambient operation that was inferior to theoretical prediction. We have been performing full analysis of the designed cavity by analytic calculation and comprehensive system simulation analysis to solve complex thermodynamics and mechanical stresses. The re-assembled cryomodule is currently under the test with a 50 kW klystron at the Fermilab A0 beamline, which will benchmark the modeling analysis. The test result will be used to design vacuum cryomodules for the 3.9 GHz deflecting mode cavity that will be employed at the ASTA facility for beam diagnostics and phase...

  2. HIGH POWER TEST OF A 3.9 GHZ 5-CELL DEFLECTING-MODE CAVITY IN A CRYOGENIC OPERATION

    Energy Technology Data Exchange (ETDEWEB)

    Shin, Young-Min; Church, Michael

    2013-11-24

    A 3.9 GHz deflecting mode (S, TM110) cavity has been long used for six-dimensional phase-space beam manipulation tests [1-5] at the A0 Photo-Injector Lab (16 MeV) in Fermilab and their extended applications with vacuum cryomodules are currently planned at the Advanced Superconducting Test Accelerator (ASTA) user facility (> 50 MeV). Despite the successful test results, the cavity, however, demonstrated limited RF performance during liquid nitrogen (LN2) ambient operation that was inferior to theoretical prediction. We have been performing full analysis of the designed cavity by analytic calculation and comprehensive system simulation analysis to solve complex thermodynamics and mechanical stresses. The re-assembled cryomodule is currently under the test with a 50 kW klystron at the Fermilab A0 beamline, which will benchmark the modeling analysis. The test result will be used to design vacuum cryomodules for the 3.9 GHz deflecting mode cavity that will be employed at the ASTA facility for beam diagnostics and phase-space control.

  3. Novel deflecting cavity design for eRHIC

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Q.; Belomestnykh, S.; Ben-Zvi, I.

    2011-07-25

    To prevent significant loss of the luminosity due to large crossing angle in the future ERL based Electron Ion Collider at BNL (eRHIC), there is a demand for crab cavities. In this article, we will present a novel design of the deflecting/crabbing 181 MHz superconducting RF cavity that will fulfil the requirements of eRHIC. The quarter-wave resonator structure of the new cavity possesses many advantages, such as compact size, high R{sub t}/Q, the absence of the same order mode and lower order mode, and easy higher order mode damping. We will present the properties and characteristics of the new cavity in detail. As the accelerator systems grow in complexity, developing compact and efficient deflecting cavities is of great interest. Such cavities will benefit situations where the beam line space is limited. The future linac-ring type electron-ion collider requires implementation of a crab-crossing scheme for both beams at the interaction region. The ion beam has a long bunches and high rigidity. Therefore, it requires a low frequency, large kicking angle deflector. The frequency of the deflecting mode for the current collider design is 181 MHz, and the deflecting angle is {approx}5 mrad for each beam. At such low frequency, the previous designs of the crab cavities will have very large dimensions, and also will be confronted by typical problems of damping the Lower Order Mode (LOM), the Same Order Mode (SOM), and as usual, the Higher Order Modes (HOM). In this paper we describe how one can use the concept of a quarter-wave (QW) resonator for a deflecting/crabbing cavity, and use its fundamental mode to deflect the beam. The simplicity of the cavity geometry and the large separation between its fundamental mode and the first HOM make it very attractive.

  4. Coupler induced monopole component and its minimization in deflecting cavities

    Directory of Open Access Journals (Sweden)

    P. K. Ambattu

    2013-06-01

    Full Text Available Deflecting cavities are used in particle accelerators for the manipulation of charged particles by deflecting or crabbing (rotating them. For short deflectors, the effect of the power coupler on the deflecting field can become significant. The particular power coupler type can introduce multipole rf field components and coupler-specific wakefields. Coupler types that would normally be considered like standard on-cell coupler, waveguide coupler, or mode-launcher coupler could have one or two rf feeds. The major advantage of a dual-feed coupler is the absence of monopole and quadrupole rf field components in the deflecting structure. However, a dual-feed coupler is mechanically more complex than a typical single-feed coupler and needs a splitter. For most applications, deflecting structures are placed in regions where there is small space hence reducing the size of the structure is very desirable. This paper investigates the multipole field components of the deflecting mode in single-feed couplers and ways to overcome the effect of the monopole component on the beam. Significant advances in performance have been demonstrated. Additionally, a novel coupler design is introduced which has no monopole field component to the deflecting mode and is more compact than the conventional dual-feed coupler.

  5. SUPERCONDUCTING RF-DIPOLE DEFLECTING AND CRABBING CAVITIES

    Energy Technology Data Exchange (ETDEWEB)

    Delayen, Jean [ODU, JLAB; De Silva, Paygalage Subashini [ODU, JLAB

    2013-09-01

    Recent interests in designing compact deflecting and crabbing structures for future accelerators and colliders have initiated the development of novel rf structures. The superconducting rf-dipole cavity is one of the first compact designs with attractive properties such as higher gradients, higher shunt impedance, the absence of lower order modes and widely separated higher order modes. Two rf-dipole designs of 400 MHz and 499 MHz have been designed, fabricated and tested as proof-of-principle designs of compact deflecting and crabbing cavities for the LHC high luminosity upgrade and Jefferson Lab 12 GeV upgrade. The first rf tests have been performed on the rf-dipole geometries at 4.2 K and 2.0 K in a vertical test assembly with excellent results. The cavities have achieved high gradients with high intrinsic quality factors, and multipacting levels were easily processed.

  6. An improved equivalent circuit model of a four rod deflecting cavity

    Science.gov (United States)

    Apsimon, R.; Burt, G.

    2017-03-01

    In this paper we present an improved equivalent circuit model for a four rod deflecting cavity which calculates the frequencies of the first four modes of the cavity as well as the RT/Q for the deflecting mode. Equivalent circuit models of RF cavities give intuition and understanding about how the cavity operates and what changes can be made to modify the frequency, without the need for RF simulations, which can be time-consuming. We parameterise a generic four rod deflecting cavity into a geometry consisting of simple shapes. Equations are derived for the line impedance of the rods and the capacitance between the rods and these are used to calculate the resonant frequency of the deflecting dipole mode as well as the lower order mode and the model is bench-marked against two test cases; the CEBAF separator and the HL-LHC 4-rod LHC crab cavity. CST and the equivalent circuit model agree within 4% for both cavities with the LOM frequency and within 1% for the deflecting frequency. RT/Q differs between the model and CST by 37% for the CEBAF separator and 25% for the HL-LHC 4-rod crab cavity; however this is sufficient for understanding how to optimise the cavity design. The model has then been utilised to suggest a method of separating the modal frequencies in the HL-LHC crab cavity and to suggest design methodologies to optimise the cavity geometries.

  7. Cryogenic Test of a Proof-of-Principle Superconducting RF-Dipole Deflecting and Crabbing Cavity

    CERN Document Server

    De Silva, S U; Delayen, Jean Roger

    2013-01-01

    Recent applications in need of compact low-frequency deflecting and crabbing cavities have initiated the design and development of new superconducting structures operating at high gradients with low losses. Previously, TM$_{110}$ -type deflecting and crabbing cavities were developed and have also been operated successfully. However, these geometries are not favorable designs for low operating frequencies. The superconducting rf-dipole cavity is the first compact deflecting and crabbing geometry that has demonstrated high gradients and high shunt impedance. Since the fundamental operating mode is the lowest mode and is widely separated from the nearest higher order mode, the rf-dipole design is an attractive geometry for effective damping of the higher order modes in high current applications. A 400 MHz rf-dipole cavity was designed, fabricated, and tested as a proof-of-principle cavity. The cavity achieved high operating gradients, and the multipacting levels were easily processed and did not reoccur.

  8. Multipole Field Effects for the Superconducting Parallel-Bar Deflecting/Crabbing Cavities

    Energy Technology Data Exchange (ETDEWEB)

    De Silva, Payagalage Subashini Uddika [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States) and Old Dominion University, Norfolk, VA (United States); Delayen, Jean Roger [Old Dominion University, Norfolk, VA (United States)

    2012-09-01

    The superconducting parallel-bar deflecting/crabbing cavity is currently being considered as one of the design options in rf separation for the Jefferson Lab 12 GeV upgrade and for the crabbing cavity for the proposed LHC luminosity upgrade. Knowledge of multipole field effects is important for accurate beam dynamics study of rf structures. The multipole components can be accurately determined numerically using the electromagnetic surface field data in the rf structure. This paper discusses the detailed analysis of those components for the fundamental deflecting/crabbing mode and higher order modes in the parallel-bar deflecting/crabbing cavity.

  9. Analysis of HOM Properties of Superconducting Parallel-Bar Deflecting/Crabbing Cavities

    Energy Technology Data Exchange (ETDEWEB)

    S.U. De Silva, J.R. Delayen

    2011-07-01

    The superconducting parallel-bar cavity is currently being considered for a number of deflecting and crabbing applications due to improved properties and compact design geometries. The 499 MHz deflecting cavity proposed for the Jefferson Lab 12 GeV upgrade and the 400 MHz crab cavity for the proposed LHC luminosity upgrade are two of the major applications. For high current applications the higher order modes must be damped to acceptable levels to eliminate any beam instabilities. The frequencies and R/Q of the HOMs and mode separation are evaluated and compared for different parallel-bar cavity designs.

  10. RF deflecting cavity design for Berkeley ultrafast X-ray source

    Energy Technology Data Exchange (ETDEWEB)

    Li, Derun; Corlett, J.

    2002-05-30

    Our proposed source for production of ultra-short (less than 100 fs FWHM) x-ray pulses utilizes a scheme for manipulation of the relatively long ({approx}2 ps) electron bunch in transverse phase-space, followed by compression of the emitted x-ray pulse in crystal optics [1]. In order to compress the x-ray pulses, RF cavities operating in a dipole mode (TM{sub 110}-like) are required to deflect the head and tail of a 2.5 GeV bunch in opposite directions. For a 2 ps duration electron bunch, an 8.5 MV deflecting voltage is required at a RF frequency of 3.9 GHz. In this paper, we will present a preliminary cavity design based on numerical simulations performed by MAFIA and URMEL codes. Seven-cell superconducting {pi} mode dipole RF cavities are proposed to provide the necessary deflecting voltage. Due to the presence of beam iris, the cavities operate in a hybrid mode where TM and TE like modes co-exist. Even on the beam axis, both magnetic and electric fields contribute to the transverse kick. Lower order monopole modes (LOMs) in the cavities may cause energy spread of the electron beam and need to be damped. The effects of the LOMs on beam dynamics are estimated. Possible damping schemes will be discussed.

  11. RF deflecting cavity design for Berkeley ultrafast X-ray source

    Science.gov (United States)

    Li, D.; Corlett, J.

    2002-05-01

    Our proposed source for production of ultra-short (less than 100 fs FWHM) x-ray pulses utilizes a scheme for manipulation of the relatively long (2 ps) electron bunch in transverse phase-space, followed by compression of the emitted x-ray pulse in crystal optics. In order to compress the x-ray pulses, RF cavities operating in a dipole mode (TM110-like) are required to deflect the head and tail of a 2.5 GeV bunch in opposite directions. For a 2 ps duration electron bunch, an 8.5 MV deflecting voltage is required at a RF frequency of 3.9 GHz. In this paper, we will present a preliminary cavity design based on numerical simulations performed by MAFIA and URMEL codes. Seven-cell superconducting p mode dipole RF cavities are proposed to provide the necessary deflecting voltage. Due to the presence of beam iris, the mavities operate in a hybrid mode where TM and TE like modes co-exist. Even on mhe beam axis, both magnetic and electric fields contribute to the transverse mick. Lower order monopole modes (LOMs) in the cavities may cause energy spread of the electron beam and need to be damped. The effects of the LOMs on beam dynamics are estimated. Possible damping schemes will be discussed.

  12. Fabrication and Testing of Deflecting Cavities for APS

    Energy Technology Data Exchange (ETDEWEB)

    Mammosser, John; Wang, Haipeng; Rimmer, Robert; Jim, Henry; Katherine, Wilson; Dhakal, Pashupati; Ali, Nassiri; Jim, Kerby; Jeremiah, Holzbauer; Genfa, Wu; Joel, Fuerst; Yawei, Yang; Zenghai, Li

    2013-09-01

    Jefferson Lab (Newport News, Virginia) in collaboration with Argonne National Laboratory (Argonne, IL) has fabricated and tested four first article, 2.8 GHz, deflecting SRF cavities, for Argonne's Short-Pulse X-ray (SPX) project. These cavities are unique in many ways including the fabrication techniques in which the cavity cell and waveguides were fabricated. These cavity subcomponents were milled from bulk large grain niobium ingot material directly from 3D CAD files. No forming of sub components was used with the exception of the beam-pipes. The challenging cavity and helium vessel design and fabrication results from the stringent RF performance requirements required by the project and operation in the APS ring. Production challenges and fabrication techniques as well as testing results will be discussed in this paper.

  13. Deflecting RF cavity design for a recirculating linac based facility for ultrafast X-ray science (LUX)

    Energy Technology Data Exchange (ETDEWEB)

    Li, Derun; Corlett, J.N.

    2003-05-01

    We report on superconducting deflecting RF cavity designs for a Recirculating Linac Based Facility for Ultrafast X-ray Science (LUX) at Lawrence Berkeley National Laboratory. The deflecting cavities operate in the lowest dipole mode and are required to produce a temporal correlation within flat electron bunches, as needed for x-ray compression in crystal optics. Deflecting voltage of up to 8.5-MV is required at 3.9-GHz. We present a 7-cell cavity design in this paper. Seven such cavities are required to generate the 8.5 MV deflecting voltage. Longitudinal and transverse impedance from LOM (lower order mode) and HOM (higher order mode) are simulated using the MAFIA code. Short-range and long-range wakefield excited through these impedances are calculated. Beam loading effects of the deflecting mode and LOM modes are estimated. Q values of the LOM monopole modes in the cavity may need to be damped to be below 10{sup 4}-10{sup 5} levels in order to maintain the required energy spread.

  14. Design and Development of Superconducting Parallel-Bar Deflecting/Crabbing Cavities

    Energy Technology Data Exchange (ETDEWEB)

    Payagalage Subashini Uddi De Silva, Jean Delayen

    2012-07-01

    The superconducting parallel-bar cavity is a deflecting/crabbing cavity with attractive properties that is being considered for a number of applications. We present the designs of a 499 MHz deflecting cavity developed for the Jefferson Lab 12 GeV Upgrade and a 400 MHz crabbing cavity for the LHC High Luminosity Upgrade. Prototypes of these two cavities are now under development and fabrication.

  15. Two-mode polarized traveling wave deflecting structure

    Institute of Scientific and Technical Information of China (English)

    谭建豪; 顾强; 方文程; 童德春; 赵振堂

    2015-01-01

    In this paper, we propose a two-mode polarizable deflecting structure, as a new concept for bunch measure-ment and beam control. With two modes of HEM11 and HEM12 operating in the same structure on horizontal and vertical directions, respectively, the operation status can be switched between the two polarization modes. They can be operated simultaneously with two independent input power sources. With two-mode deflecting structure, the bunch distortion caused by the geometric wake-fields in the accelerating structure can be mea-sured by one structure.

  16. LIGHT SOURCE: RF deflecting cavity for bunch length measurement in Tsinghua Thomson scattering X-ray source

    Science.gov (United States)

    Shi, Jia-Ru; Chen, Huai-Bi; Tang, Chuan-Xiang; Huang, Wen-Hui; Du, Ying-Chao; Zheng, Shu-Xin; Ren, Li

    2009-06-01

    An RF deflecting cavity used for bunch length measurement has been designed and fabricated at Tsinghua University for the Thomson Scattering X-Ray Source. The cavity is a 2856 MHz, π-mode, 3-cell standing-wave cavity, to diagnose the 3.5 MeV beam produced by photocathode electron gun. With a larger power source, the same cavity will again be used to measure the accelerated beam with energy of 50 MeV before colliding with the laser pulse. The RF design using MAFIA for both the cavity shape and the power coupler is reviewed, followed by presenting the fabrication procedure and bench measurement results of two cavities.

  17. Laser heating of a cavity versus a plane surface for metal targets utilizing photothermal deflection measurements

    Science.gov (United States)

    Jeong, S. H.; Greif, R.; Russo, R. E.

    1996-08-01

    The effects of a cylindrical cavity in a metal surface on the energy coupling of a laser beam with the solid were investigated by using a photothermal deflection technique. The photothermal deflection of a probe beam over the cavity was measured while the bottom of the cavity was heated with a Nd-YAG laser with a wavelength of 1064 nm. Cavities in three different materials and with two different aspect ratios were used for the experiment. Temperature distributions in the solid and the surrounding air were computed numerically and used to calculate photothermal deflections for cavity heating and for plane surface heating. Reflection of the heating laser beam inside the cavity increased the photothermal deflection amplitude significantly with larger increases for materials with larger thermal diffusivity. The computed photothermal deflections agreed more closely with the experimental results when reflection of the heating laser beam inside the cavity was included in the numerical model. The overall energy coupling between a heating laser and a solid is enhanced by a cavity.

  18. Deflection and focusing of charged particles by cavities of general shape

    Science.gov (United States)

    Hinderer, G.

    1991-04-01

    The integrated transverse momentum change of a charged particle in the rf field of a cavity can be related to the change of its voltage gain due to a virtual transverse displacement of its orbit. Formulas for the particle deflection are derived, which are a generalisation of the Panofsky-Wenzel theorem to an arbitrary cavity shape and to curved orbits through the cavity. In addition, some useful formulas for the transverse and longitudinal focusing are presented.

  19. Leaky Modes of Dielectric Cavities

    CERN Document Server

    Mansuripur, Masud; Jakobsen, Per

    2016-01-01

    In the absence of external excitation, light trapped within a dielectric medium generally decays by leaking out (and also by getting absorbed within the medium). We analyze the leaky modes of a parallel-plate slab, a solid glass sphere, and a solid glass cylinder, by examining those solutions of Maxwell's equations (for dispersive as well as non-dispersive media) which admit of a complex-valued oscillation frequency. Under certain circumstances, these leaky modes constitute a complete set into which an arbitrary distribution of the electromagnetic field residing inside a dielectric body can be expanded. We provide completeness proofs, and also present results of numerical calculations that illustrate the relationship between the leaky modes and the resonances of dielectric cavities formed by a simple parallel-plate slab, a glass sphere, and a glass cylinder.

  20. Higher Order Mode Filter Design for Double Quarter Wave Crab Cavity for the LHC High Luminosity Upgrade

    CERN Document Server

    Xiao, B P; Ben-Zv, I; Burt, Graeme Campbell; Calaga, Rama; Capatina, Ofelia; Hall, B; Jones, T; Skaritka, J; Verdú-Andrés, S; Wu, Q

    2015-01-01

    A Double Quarter Wave Crab Cavity (DQWCC) was designed for the Large Hadron Collider (LHC) luminosity upgrade. A compact Higher Order Mode (HOM) filter with wide stop band at the deflecting mode is developed for this cavity. Multi-physics finite element simulation results are presented. The integration of this design to the cavity cryomodule is described.

  1. Higher order mode filter design for double quarter wave crab cavity for the LHC high luminosity upgrade

    Energy Technology Data Exchange (ETDEWEB)

    Xiao, B. [Brookhaven National Lab. (BNL), Upton, NY (United States); Belomestnykh, S. [Brookhaven National Lab. (BNL), Upton, NY (United States); Stony Brook Univ., NY (United States); Ben-Zvi, I. [Brookhaven National Lab. (BNL), Upton, NY (United States); Stony Brook Univ., NY (United States); Burt, G. [Lancaster Univ. (United Kingdom); Calaga, R. [European Organization for Nuclear Research (CERN), Geneva (Switzerland); Capatina, O. [European Organization for Nuclear Research (CERN), Geneva (Switzerland); Hall, B. [Lancaster Univ. (United Kingdom); Jones, T. [Science and Technology Facilities Council (STFC), Daresbury (United Kingdom). Daresbury Lab.; Skaritka, J. [Brookhaven National Lab. (BNL), Upton, NY (United States); Verdu-Andres, S. [Brookhaven National Lab. (BNL), Upton, NY (United States); Wu, Q. [Brookhaven National Lab. (BNL), Upton, NY (United States)

    2015-05-03

    A Double Quarter Wave Crab Cavity (DQWCC) was designed for the Large Hadron Collider (LHC) luminosity upgrade. A compact Higher Order Mode (HOM) filter with wide stop band at the deflecting mode is developed for this cavity. Multiphysics finite element simulation results are presented. The integration of this design to the cavity cryomodule is described.

  2. Dispersion of coupled mode-gap cavities

    CERN Document Server

    Lian, Jin; Yüce, Emre; De Rossi, Sylvain Combrié Alfredo; Mosk, Allard P

    2015-01-01

    The dispersion of a CROW made of photonic crystal mode-gap cavities is pronouncedly asymmetric. This asymmetry cannot be explained by the standard tight binding model. We show that the fundamental cause of the asymmetric dispersion is the fact that the cavity mode profile itself is dispersive, i.e., the mode wave function depends on the driving frequency, not the eigenfrequency. This occurs because the photonic crystal cavity resonances do not form a complete set. By taking into account the dispersive mode profile, we formulate a mode coupling model that accurately describes the asymmetric dispersion without introducing any new free parameters.

  3. Deflecting cavity dynamics for time-resolved machine studies of SXFEL user facility

    CERN Document Server

    Song, Minghao; Liu, Bo; Wang, Dong

    2016-01-01

    Radio frequency deflectors are widely used for time-resolved electron beam energy, emittance and radiation profile measurements in modern free electron laser facilities. In this paper, we present the beam dynamics aspects of the deflecting cavity of SXFEL user facility, which is located at the exit of the undulator. With a targeted time resolution around 10 fs, it is expected to be an important tool for time-resolved commissioning and machine studies for SXFEL user facility.

  4. Slice emittance measurement for photocathode RF gun with solenoid scanning and RF deflecting cavity

    Science.gov (United States)

    Li, Chen; Huang, WenHui; Du, YingChao; Yan, LiXin; Tang, ChuanXiang

    2011-12-01

    The radiation of high-gain short-wavelength free-electron laser depends on the slice transverse emittance of the electron bunch. This essay introduces the method of slice emittance measurement, and shows the brief setup of this experiment using the solenoid scanning and RF deflecting cavity at Tsinghua University. The preliminary experimental results show that the slice rms emittance of the electron bunch generated by photocathode RF gun has considerable variations along the bunch and is typically less than 0.55 mm mrad for the laser rms radius of 0.4 mm.

  5. Slice emittance measurement for photocathode RF gun with solenoid scanning and RF deflecting cavity

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    The radiation of high-gain short-wavelength free-electron laser depends on the slice transverse emittance of the electron bunch. This essay introduces the method of slice emittance measurement, and shows the brief setup of this experiment using the solenoid scanning and RF deflecting cavity at Tsinghua University. The preliminary experimental results show that the slice rms emittance of the electron bunch generated by photocathode RF gun has considerable variations along the bunch and is typically less than 0.55 mm mrad for the laser rms radius of 0.4 mm.

  6. Multi-Mode Cavity Accelerator Structure

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Yong [Yale Univ., New Haven, CT (United States); Hirshfield, Jay Leonard [Omega-P R& D, Inc., New Haven, CT (United States)

    2016-11-10

    This project aimed to develop a prototype for a novel accelerator structure comprising coupled cavities that are tuned to support modes with harmonically-related eigenfrequencies, with the goal of reaching an acceleration gradient >200 MeV/m and a breakdown rate <10-7/pulse/meter. Phase I involved computations, design, and preliminary engineering of a prototype multi-harmonic cavity accelerator structure; plus tests of a bimodal cavity. A computational procedure was used to design an optimized profile for a bimodal cavity with high shunt impedance and low surface fields to maximize the reduction in temperature rise ΔT. This cavity supports the TM010 mode and its 2nd harmonic TM011 mode. Its fundamental frequency is at 12 GHz, to benchmark against the empirical criteria proposed within the worldwide High Gradient collaboration for X-band copper structures; namely, a surface electric field Esurmax< 260 MV/m and pulsed surface heating ΔTmax< 56 °K. With optimized geometry, amplitude and relative phase of the two modes, reductions are found in surface pulsed heating, modified Poynting vector, and total RF power—as compared with operation at the same acceleration gradient using only the fundamental mode.

  7. Mode-locked Lasers Applied to Deflecting a Near Earth Object on Collision Course with Earth

    CERN Document Server

    Fork, Richard; Burgess, Luke; Bergstue, Grant

    2013-01-01

    We consider synchronized trains of sub-picosecond pulses generated by mode-locked lasers applied to deflection of near Earth objects (NEO) on collision course with Earth. Our method is designed to avoid a predicted collision of the NEO with Earth by at least the diameter of Earth. We estimate deflecting a 10,000 MT NEO, such as the asteroid which struck Earth near Chelyabinsk, Russia to be feasible within several months using average power in the ten kilowatt range. We see this deflection method as scalable to larger NEO to a degree not possible using continuous laser systems.

  8. Observing mode propagation inside a laser cavity

    CSIR Research Space (South Africa)

    Naidoo, Darryl

    2012-05-01

    Full Text Available The mode inside a laser cavity may be understood as the interference of two counter-propagating waves, referred to as the forward and backward waves, respectively. We outline a simple experimental procedure, which does not require any additional...

  9. Comparative research on the methods for measuring the mode deflection angle of cylindrical resonator gyroscope

    Science.gov (United States)

    Wang, Kai; Fan, Zhenfang; Wang, Dongya; Wang, Yanyan; Pan, Yao; Qu, Tianliang; Xu, Guangming

    2016-10-01

    The existence of mode deflection angle in the cylindrical resonator gyroscope (CRG) leads to the signal drift on the detecting nodes of the gyro vibration and significantly decreases the performance of the CRG. Measuring the mode deflection angle efficiently is the foundation of tuning for the imperfect cylindrical shell resonator. In this paper, an optical method based on the measuring gyroscopic resonator's vibration amplitude with the laser Doppler vibrometer and an electrical method based on measuring the output voltage of the electrodes on the resonator are both presented to measure the mode deflection angle. Comparative experiments were implemented to verify the methodology and the results show that both of the two methods could recognize the mode deflection angle efficiently. The precision of the optical method relies on the number and position of testing points distributed on the resonator. The electrical method with simple circuit shows high accuracy of measuring in a less time compared to the optical method and its error source arises from the influence of circuit noise as well as the inconsistent distribution of the piezoelectric electrodes.

  10. Differential cavity mode spectroscopy: A new cavity enhanced technique for the detection of weak transitions

    Energy Technology Data Exchange (ETDEWEB)

    Vine, Glenn de [Centre for Gravitational Physics, Faculty of Science, The Australian National University, Canberra ACT 0200 (Australia)], E-mail: glenn.devine@jpl.nasa.gov; McClelland, David E.; Gray, Malcolm B. [Centre for Gravitational Physics, Faculty of Science, The Australian National University, Canberra ACT 0200 (Australia)

    2008-06-16

    We present a new cavity enhanced, continuous wave spectroscopic technique for the detection of weak atomic and molecular transitions. Differential Cavity Mode Spectroscopy (DCMS) measures the difference in absorption between two adjacent cavity longitudinal modes to yield a highly sensitive, yet relatively simple, cavity enhanced spectroscopic technique. In addition this relative absorption measurement is, to first order, independent of both laser frequency noise and cavity acoustic noise. Here we present both a theoretical description of this new technique and an initial experimental demonstration.

  11. Rigorous analysis of trapped modes in accelerating cavities

    Directory of Open Access Journals (Sweden)

    Rolf Schuhmann

    2000-12-01

    Full Text Available We report the development of different algorithms for the calculation of quality factors of eigenmodes in accelerating cavities, which have resonance frequencies above the cutoff frequency of the beam tubes. The analysis is based on a discretization of such cavity structures by the finite integration technique, and the radiation at the open boundaries is systematically taken into account by different approaches in time and frequency domain. Results indicate that even single cell cavities of the TESLA type show Q values of 10^{3} and multicell cavities values in excess of 10^{4}. Thus these modes may cause considerable beam instabilities. Comparison with the conventional method of analyzing closed cavities and identifying modes with little change in frequency as a function of boundary condition shows qualitative differences. Some modes from the closed cavity model do not exist in the open structure and thus would be misinterpreted as trapped modes when only a closed cavity analysis is employed.

  12. Interaction between dual cavity modes in a planar photonic microcavity

    Science.gov (United States)

    Noble, Elizabeth; Nair, Rajesh V.; Jagatap, B. N.

    2016-10-01

    We theoretically study the interaction between dual cavity modes in a planar photonic microcavity structure in the optical communication wavelength range. The merging and splitting of cavity mode is analysed with realistic microcavity structures. The merging of dual cavity resonance into a single cavity resonance is achieved by changing the number of layers between the two cavities. The splitting of single cavity resonance into dual cavity resonance is obtained with an increase in the reflectivity of mirrors in the front and rear side of the microcavity structure. The threshold condition for the merging and splitting of cavity mode is established in terms of structural parameters. The physical origin of the merging of dual cavity modes into a single cavity resonance is discussed in terms of the electric field intensity distribution in the microcavity structure. The microcavity structure with dual cavity modes is useful for the generation of entangled photon pairs, for achieving the strong-coupling regime between exciton and photon and for high-resolution multi-wavelength filters in optical communication.

  13. Observation of Three Mode Parametric Interactions in Long Optical Cavities

    CERN Document Server

    Zhao, C; Fan, Y; Slagmolen, S Gras B J J; Miao, H; Blair, P Barriga D G; Hosken, D J; Brooks, A F; Veitch, P J; Mudge, D; Munch, J

    2008-01-01

    We report the first observation of three-mode opto-acoustic parametric interactions of the type predicted to cause parametric instabilities in an 80 m long, high optical power cavity that uses suspended sapphire mirrors. Resonant interaction occurs between two distinct optical modes and an acoustic mode of one mirror when the difference in frequency between the two optical cavity modes is close to the frequency of the acoustic mode. Experimental results validate the theory of parametric instability in high power optical cavities.

  14. THE EFFECT OF CORRUGATED ELEMENTS THICKNESS ON THE DEFLECTED MODE OF CORRUGATED METAL STRUCTURES

    Directory of Open Access Journals (Sweden)

    V. V. Kovalchuk

    2015-06-01

    Full Text Available Purpose. The work provides research the deflected mode and calculation the relative deformation of vertical and horizontal diameters of corrugated metal structures (CMS, horizontal ellipse type, and cross section in their interaction with soil backfill depending on the thickness of corrugated metal pipe. Such studies are required for optimal design of CMS, establishing the causes of defects timely, appropriate engineering solutions to improve the bearing capacity of the CMS and reasonable use of funds for their construction or rehabilitation of existing transportation facilities using corrugated metal pipes. Methodology. Stresses and stability calculations of CMS form are conducted using the developed mathematical algorithm in program environment Mathcad 14. In these studies different thickness of corrugated metal pipe were assigned, and further calculations were carried out at the design value of backfill soil compaction degree and magnitude of dynamic loading of railway transport. Findings. From the calculations is determined that the most influence the thickness of the corrugated metal pipe has on the strength in the calculation of the normal stresses and value of the vertical pipe strains. Therefore, the calculated parameters in the design of corrugated metal structures with small filling heights (from 1.2 m to 3 m above its peak is calculation of the strength by the normal stresses and determination of the vertical deformation of the pipe. Originality. For the first time, calculations of the deflected mode and relative deformations of vertical and horizontal cross-sectional diameters of CMS, horizontal ellipse type in the interaction with soil backfill. The factors complex was taken into account the backfill soil compaction degree, the value of dynamic loading of railway transport and different thickness of corrugated metal pipe. Practical value. The results of the deflected mode of corrugated metal structures such as horizontal ellipse of

  15. Higher Order Mode Properties of Superconducting Two-Spoke Cavities

    Energy Technology Data Exchange (ETDEWEB)

    Hopper, C. S.; Delayen, J. R.; Olave, R. G.

    2011-07-01

    Multi-Spoke cavities lack the cylindrical symmetry that many other cavity types have, which leads to a more complex Higher Order Mode (HOM) spectrum. In addition, spoke cavities offer a large velocity acceptance which means we must perform a detailed analysis of the particle velocity dependence for each mode's R/Q. We present here a study of the HOM properties of two-spoke cavities designed for high-velocity applications. Frequencies, R/Q and field profiles of HOMs have been calculated and are reported.

  16. Coherent control of double deflected anomalous modes in ultrathin trapezoid-shaped slit metasurface

    Science.gov (United States)

    Zhu, Z.; Liu, H.; Wang, D.; Li, Y. X.; Guan, C. Y.; Zhang, H.; Shi, J. H.

    2016-11-01

    Coherent light-matter interaction in ultrathin metamaterials has been demonstrated to dynamically modulate intensity, polarization and propagation direction of light. The gradient metasurface with a transverse phase variation usually exhibits an anomalous refracted beam of light dictated by so-called generalized Snell’s law. However, less attention has been paid to coherent control of the metasurface with multiple anomalous refracted beams. Here we propose an ultrathin gradient metasurface with single trapezoid-shaped slot antenna as its building block that allows one normal and two deflected transmitted beams. It is numerically demonstrated that such metasurface with multiple scattering modes can be coherently controlled to modulate output intensities by changing the relative phase difference between two counterpropagating coherent beams. Each mode can be coherently switched on/off and two deflected anomalous beams can be synchronously dictated by the phase difference. The coherent control effect in the trapezoid-shaped slit metasurface will offer a promising opportunity for multichannel signals modulation, multichannel sensing and wave front shaping.

  17. Rapid cavity prototyping using mode matching and globalised scattering matrix

    CERN Document Server

    Shinton, I

    2009-01-01

    Cavity design using traditional mesh based numerical means (such as the finite element or finite difference methods) require large mesh calculations in order to obtain accurate values and cavity optimisation is often not achieved. Here we present a mode matching scheme which utilises a globalised scattering matrix approach that allows cavities with curved surfaces (i.e. cavities with elliptical irises and or equators) to be accurately simulated allowing rapid cavity prototyping and optimisation to be achieved. Results on structures in the CLIC main

  18. Acoustic mode coupling of two facing, shallow cylindrical cavities

    Science.gov (United States)

    McCarthy, Philip; Ekmekci, Alis

    2016-11-01

    Cavity mode excitation by grazing flows is a well-documented source for noise generation. Similarly to their rectangular equivalents, single cylindrical cavities have been shown to exhibit velocity dependent self-sustaining feedback mechanisms that produce significant tonal noise. The present work investigates the effect of cavity mode coupling on the tonal noise generation for two facing, shallow cylindrical cavities. This geometric arrangement may occur for constrained flows, such as those within ducts, silencers or between aircraft landing gear wheels. For the latter configuration, the present study has observed that the tonal frequency dependence upon the freestream Mach number, associated with the single cavity feedback mechanism, no longer holds true. Instead, two simultaneously present and distinct large amplitude tones that are independent (in frequency) of speed, propagate to the far field. These two, fixed frequency tones are attributable to the first order transverse mode, and the first order transverse and azimuthal modes for the two combined cavities and the volume between them. Altering either the cavity aspect ratio or the inter-cavity spacing thus changes the acoustic resonant volume and translates the centre frequencies of the observed tones correspondingly. The authors would like to thank Bombardier and Messier-Bugatti-Dowty for their continued support.

  19. Higher Order Reentrant Post Modes in Cylindrical Cavities

    CERN Document Server

    McAllister, Ben T; Parker, Stephen R; Tobar, Michael E

    2016-01-01

    Reentrant cavities are microwave resonant devices employed in a number of different areas of physics. They are appealing due to their simple frequency tuning mechanism, which offers large tuning ranges. Reentrant cavities are, in essence, 3D lumped LC circuits consisting of a conducting central post embedded in a resonant cavity. The lowest order reentrant mode (which transforms from the TM010 mode) has been extensively studied in past publications. In this work we show the existence of higher order reentrant post modes (which transform from the TM01n mode family). We characterize these new modes in terms of their frequency tuning, filling factors and quality factors, as well as discuss some possible applications of these modes in fundamental physics tests.

  20. Power Enhancement Cavity for Burst-Mode Laser Pulses

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Yun [ORNL

    2015-01-01

    We demonstrate a novel optical cavity scheme and locking method that can realize the power enhancement of picosecond UV laser pulses operating at a burst mode with arbitrary burst (macropulse) lengths and repetition rates.

  1. Temperature switching of cavity modes in InN microcrystals

    Energy Technology Data Exchange (ETDEWEB)

    Kazanov, D. R., E-mail: kazanovdr@gmail.com; Kaibyshev, V. H.; Davydov, V. Yu.; Smirnov, A. N.; Jmerik, V. N.; Kuznetsova, N. V.; Kopiev, P. S.; Ivanov, S. V.; Shubina, T. V. [Russian Academy of Sciences, Ioffe Physical–Technical Institute (Russian Federation)

    2015-11-15

    InN optical cavities supporting low-order whispering-gallery modes up to room temperature are formed by molecular-beam epitaxy on patterned substrates. The observed switching of the mode type with increasing temperature is explained in terms of changes in the optical parameters due to a shift of the absorption edge and modification of its shape. Modeling taking into account a variation in the refractive index reproduces the typical distributions of the electromagnetic-field intensity in the cavities.

  2. Study of Gain in C-Band Deflection Cavities for a Frequency-Doubling Magnicon Amplifier

    Science.gov (United States)

    1993-03-26

    surface cleanliness , and background vacuum pressure. The threshold for multipactor in the drive cavity, in the presence of the axial magnetic field, was...different degrees of surface cleanliness . In order to make an unambiguous test of the linear interaction theory, the experimental gain measurements were

  3. Mode interactions of a high-subsonic deep cavity

    Science.gov (United States)

    Chen, Zhenli; Adams, Nikolaus A.

    2017-05-01

    To understand the interactions of the acoustic modes associated with the tunnel walls and the cavity oscillations in the experiment, flows over a deep cavity having a length-to-depth ratio L/D = 0.42 at high subsonic speeds with and without an upper tunnel wall were investigated by using an implicit large-eddy simulation with an adaptive local deconvolution method. The results of the simulations with the upper tunnel wall converge well to the experimental results as the resolution increases. However, in the simulations without the upper tunnel wall the flow converges to a different mean state. The mode interactions were analyzed by using a Dynamic Mode Decomposition (DMD) method based on a memory-efficient snapshot algorithm. It was found that nearly trapped global modes, which have almost zero upstream and downstream radiation, can occur. The interactions of the trapped modes, the acoustic resonant modes in the cavity, and the shear-layer modes can be observed in the DMD modes of the flow with the upper tunnel wall, which results in the enhancement of harmonic modes and the existence of higher-order modes. In the flow without the upper tunnel wall, the pressure waves can transmit freely away from the cavity, but the interactions of the acoustic resonant modes and the shear-layer modes can also be observed when the frequencies of both kinds of modes coincide. The effects of the ratio of the cavity depth to the tunnel height (D/H) on the formation of trapped modes were also investigated. As the ratio D/H decreases, the frequency window of the trapped modes shrinks and finally closes, which is consistent with a theoretical model. It can be concluded that the effects of the upper tunnel wall on the dynamics of the cavity flow are strong and are promoted by the interactions of different kinds of modes. The appearance and enhancement of high order harmonic modes in the high-subsonic deep cavity are due to the effects of the trapped modes, but are not due to the directly

  4. Topological protection of photonic mid-gap cavity modes

    CERN Document Server

    Noh, Jiho; Huang, Sheng; Collins, Matthew J; Chen, Kevin; Hughes, Taylor L; Rechtsman, Mikael C

    2016-01-01

    Defect modes in two-dimensional periodic photonic structures have found use in a highly diverse set of optical devices. For example, photonic crystal cavities confine optical modes to subwavelength volumes and can be used for Purcell enhancement of nonlinearity, lasing, and cavity quantum electrodynamics. Photonic crystal fiber defect cores allow for supercontinuum generation and endlessly-single-mode fibers with large cores. However, these modes are notoriously fragile: small changes in the structure can lead to significant detuning of resonance frequency and mode volume. Here, we show that a photonic topological crystalline insulator structure can be used to topologically protect the resonance frequency to be in the middle of the band gap, and therefore minimize the mode volume of a two-dimensional photonic defect mode. We experimentally demonstrate this in a femtosecond-laser-written waveguide array, a geometry akin to a photonic crystal fiber. The topological defect modes are determined by a topological i...

  5. Cavity BPM with Dipole-Mode-Selective Coupler

    Energy Technology Data Exchange (ETDEWEB)

    Li, Zenghai; Johnson, Ronald; Smith, Stephen R.; /SLAC; Naito, Takashi; /KEK, Tsukuba; Rifkin, Jeffrey

    2006-06-21

    In this paper, we present a novel position sensitive signal pickup scheme for a cavity BPM. The scheme utilizes the H-plane of the waveguide to couple magnetically to the side of the cavity, which results in a selective coupling to the dipole mode and a total rejection of the monopole mode. This scheme greatly simplifies the BPM geometry and relaxes machining tolerances. We will present detailed numerical studies on such a cavity BPM, analyze its resolution limit and tolerance requirements for a nanometer resolution. Finally present the measurement results of a X-band prototype.

  6. The Role of Mode Match in Asymmetric Fiber Cavities

    CERN Document Server

    Bick, Andreas; Christoph, Philipp; Hellmig, Ortwin; Heinze, Jannes; Sengstock, Klaus; Becker, Christoph

    2015-01-01

    We study and realize asymmetric fiber-based cavities with optimized mode match to achieve high reflectivity on resonance. This is especially important for mutually coupling two physical systems via light fields, e.g. in quantum hybrid systems. Our detailed theoretical and experimental analysis reveals that on resonance the interference effect between the directly reflected non-modematched light and the light leaking back out of the cavity can lead to large unexpected losses due to the mode filtering of the incoupling fiber. Strong restrictions for the cavity design result out of this effect and we show that planar-concave cavities are clearly best suited. We validate our analytical model using numerical calculations and demonstrate an experimental realization of an asymmetric fiber Fabry-P\\'erot cavity with optimized parameters.

  7. The role of mode match in fiber cavities

    Energy Technology Data Exchange (ETDEWEB)

    Bick, A.; Staarmann, C.; Christoph, P. [ZOQ (Zentrum für Optische Quantentechnologien) Universität Hamburg, Luruper Chaussee 149, 22761 Hamburg (Germany); Hellmig, O.; Heinze, J. [ILP (Institut für Laserphysik) Universität Hamburg, Luruper Chaussee 149, 22761 Hamburg (Germany); Sengstock, K.; Becker, C., E-mail: cbecker@physnet.uni-hamburg.de [ZOQ (Zentrum für Optische Quantentechnologien) Universität Hamburg, Luruper Chaussee 149, 22761 Hamburg (Germany); ILP (Institut für Laserphysik) Universität Hamburg, Luruper Chaussee 149, 22761 Hamburg (Germany)

    2016-01-15

    We study and realize asymmetric fiber-based cavities with optimized mode match to achieve high reflectivity on resonance. This is especially important for mutually coupling two physical systems via light fields, e.g., in quantum hybrid systems. Our detailed theoretical and experimental analysis reveals that on resonance, the interference effect between the directly reflected non-modematched light and the light leaking back out of the cavity can lead to large unexpected losses due to the mode filtering of the incoupling fiber. Strong restrictions for the cavity design result out of this effect and we show that planar-concave cavities are clearly best suited. We validate our analytical model using numerical calculations and demonstrate an experimental realization of an asymmetric fiber Fabry-Pérot cavity with optimized parameters.

  8. Field flatness tuning of TM110 mode cavities with closely spaced modes

    Energy Technology Data Exchange (ETDEWEB)

    Leo Bellantoni et al.

    2003-10-31

    Superconducting cavities for the CKM RF separated kaon beamline at Fermilab have modes that are closely spaced compared to the resonance bandwidths when warm, and this complicates the field flatness (warm) tuning process. Additionally, it is necessary to maintain the azimuthal orientation of the mode during the tuning deformations. the authors present two analytic techniques to warm-tune cavities with overlapping modes, a finite-element analysis of the tuning process, the design of a warm tuner which maintains mode polarization, and the results of tuning a cavity in which initial manufacturing variations caused the desired {pi} and nearby {pi}-1 modes to be indistinguishable before field flatness tuning.

  9. Cavity Mode Frequencies and Large Optomechanical Coupling in Two-Membrane Cavity Optomechanics

    CERN Document Server

    Li, J; Malossi, N; Vitali, D

    2015-01-01

    We study the cavity mode frequencies of a Fabry-Perot cavity containing two vibrating dielectric membranes and the corresponding optomechanical coupling. Due to optical interference, extremely large optomechanical coupling of the membrane relative motion is achieved when the two membranes are placed very close to a resonance of the inner cavity formed by the two membranes, and in the limit of highly reflective membranes. The upper bound of the coupling strength is given by the optomechanical coupling associated with the much shorter inner cavity, consistently with the analysis of A. Xuereb et al., Phys. Rev. Lett. 109, 223601 (2012).

  10. Single transverse mode selectively oxidized vertical cavity lasers

    Energy Technology Data Exchange (ETDEWEB)

    CHOQUETTE,KENT D.; GEIB,KENT M.; BRIGGS,RONALD D.; ALLERMAN,ANDREW A.; HINDI,JANA JO

    2000-04-26

    Vertical cavity surface emitting lasers (VCSELs) which operate in multiple transverse optical modes have been rapidly adopted into present data communication applications which rely on multi-mode optical fiber. However, operation only in the fundamental mode is required for free space interconnects and numerous other emerging VCSEL applications. Two device design strategies for obtaining single mode lasing in VCSELs based on mode selective loss or mode selective gain are reviewed and compared. Mode discrimination is attained with the use of a thick tapered oxide aperture positioned at a longitudinal field null. Mode selective gain is achieved by defining a gain aperture within the VCSEL active region to preferentially support the fundamental mode. VCSELs which exhibit greater than 3 mW of single mode output power at 850 nm with mode suppression ratio greater than 30 dB are reported.

  11. Multilongitudinal-mode model for cleaved coupled-cavity lasers

    Science.gov (United States)

    van de Capelle, J. P.; Baets, R.; Lagasse, P. E.

    1987-02-01

    The multilongitudinal-mode model for the analysis of cleaved coupled-cavity lasers proposed by Van de Capelle et al. (1984) is described in full detail. The model includes the optical interactions between the two cavities as well as the noise (spontaneous emission) in each of the resonators. It takes several longitudinal modes into account simultaneously and solves the nonlinear field equations self-consistently, together with a nonlinear resonance condition for each longitudinal mode. These conditions are coupled with each other through the nonlinearity of the laser medium. The results of this model are compared with those from an analytic model based on an effective mirror concept.

  12. Time-of-flight electron energy loss spectroscopy using TM110 deflection cavities

    Directory of Open Access Journals (Sweden)

    W. Verhoeven

    2016-09-01

    Full Text Available We demonstrate the use of two TM110 resonant cavities to generate ultrashort electron pulses and subsequently measure electron energy losses in a time-of-flight type of setup. The method utilizes two synchronized microwave cavities separated by a drift space of 1.45 m. The setup has an energy resolution of 12 ± 2 eV FWHM at 30 keV, with an upper limit for the temporal resolution of 2.7 ± 0.4 ps. Both the time and energy resolution are currently limited by the brightness of the tungsten filament electron gun used. Through simulations, it is shown that an energy resolution of 0.95 eV and a temporal resolution of 110 fs can be achieved using an electron gun with a higher brightness. With this, a new method is provided for time-resolved electron spectroscopy without the need for elaborate laser setups or expensive magnetic spectrometers.

  13. Time-of-flight electron energy loss spectroscopy using TM110 deflection cavities.

    Science.gov (United States)

    Verhoeven, W; van Rens, J F M; van Ninhuijs, M A W; Toonen, W F; Kieft, E R; Mutsaers, P H A; Luiten, O J

    2016-09-01

    We demonstrate the use of two TM110 resonant cavities to generate ultrashort electron pulses and subsequently measure electron energy losses in a time-of-flight type of setup. The method utilizes two synchronized microwave cavities separated by a drift space of 1.45 m. The setup has an energy resolution of 12 ± 2 eV FWHM at 30 keV, with an upper limit for the temporal resolution of 2.7 ± 0.4 ps. Both the time and energy resolution are currently limited by the brightness of the tungsten filament electron gun used. Through simulations, it is shown that an energy resolution of 0.95 eV and a temporal resolution of 110 fs can be achieved using an electron gun with a higher brightness. With this, a new method is provided for time-resolved electron spectroscopy without the need for elaborate laser setups or expensive magnetic spectrometers.

  14. Time-of-flight electron energy loss spectroscopy using TM110 deflection cavities

    Science.gov (United States)

    Verhoeven, W.; van Rens, J. F. M.; van Ninhuijs, M. A. W.; Toonen, W. F.; Kieft, E. R.; Mutsaers, P. H. A.; Luiten, O. J.

    2016-01-01

    We demonstrate the use of two TM110 resonant cavities to generate ultrashort electron pulses and subsequently measure electron energy losses in a time-of-flight type of setup. The method utilizes two synchronized microwave cavities separated by a drift space of 1.45 m. The setup has an energy resolution of 12 ± 2 eV FWHM at 30 keV, with an upper limit for the temporal resolution of 2.7 ± 0.4 ps. Both the time and energy resolution are currently limited by the brightness of the tungsten filament electron gun used. Through simulations, it is shown that an energy resolution of 0.95 eV and a temporal resolution of 110 fs can be achieved using an electron gun with a higher brightness. With this, a new method is provided for time-resolved electron spectroscopy without the need for elaborate laser setups or expensive magnetic spectrometers. PMID:27704035

  15. INFLUENCE OF DRAWING SPEED ON THE TEMPERATURE AND DEFLECTED MODE IN WIRE OF HIGH-CARBON STEEL

    Directory of Open Access Journals (Sweden)

    M. N. Vereshchagin

    2008-01-01

    Full Text Available The calculation of deflected mode and temperature fields with the help of the method of finite elements for zones of wire deformation in dies for current and new technology of drawing of wire with diameter 0,41 mm is carried out.

  16. Control of cavity modes in coupled periodic waveguides

    DEFF Research Database (Denmark)

    Sukhorukov, Andrey A.; Lavrinenko, Andrei; Ha, Sangwoo

    2009-01-01

    are brought closer. We show that the longitudinal shift enables flexible control over the fundamental modes, which frequency detuning can be reduced down to zero. Our coupled-mode theory analysis reveals an intrinsic link between the mode tuning and the transformation of slow-light dispersion at the photonic...... band-edge. We illustrate our approach through direct numerical modelling of cavities created in arrays of dielectric rods, nanobeam structures, and two-dimensional photonic-crystal waveguides....

  17. Quantum simulation of Dirac fermion mode, Majorana fermion mode and Majorana-Weyl fermion mode in cavity QED lattice

    OpenAIRE

    Sarkar, Sujit

    2014-01-01

    Quantum simulation aims to simulate a quantum system using a controble laboratory system that underline the same mathematical model. Cavity QED lattice system is that prescribe system to simulate the relativistic quantum effect. We quantum simulate the Dirac fermion mode, Majorana fermion mode and Majorana-Weyl fermion mode and a crossover between them in cavity QED lattice. We also present the different analytical relations between the field operators for different mode excitations.

  18. Single transverse mode selectively oxidized vertical cavity lasers

    Energy Technology Data Exchange (ETDEWEB)

    CHOQUETTE,KENT D.

    2000-04-18

    Vertical cavity surface emitting laser (VCSEL) sources have been adopted into Gigabit Ethernet applications in a remarkably short time period. VCSELs are particularly suitable for multimode optical fiber local area networks (LANs), due to their reduced threshold current, circular output beam, and inexpensive and high volume manufacture. Moreover, selectively oxidized VCSELs are nearly ideal LAN sources since the oxide aperture within the laser cavity produces strong electrical and optical confinement which enables high electrical to optical conversion efficiency and minimal modal discrimination allowing emission into multiple transverse optical modes. In addition to the large demand for multimode lasers, VCSELs which emit into a single optical mode are also increasingly sought for emerging applications, which include data communication with single mode optical fiber, bar code scanning, laser printing, optical read/write heads, and modulation spectroscopy. To achieve single mode selectively oxidized VCSELs is a challenging task, since the inherent index confinement within these high performance lasers is very large.

  19. Fine tuning of micropillar cavity modes through repetitive oxidations

    CERN Document Server

    Bakker, Morten P; Snijders, Henk; Truong, Tuan-Ahn; Petroff, Pierre M; Bouwmeester, Dirk; van Exter, Martin P

    2013-01-01

    Repetitive wet thermal oxidations of a tapered oxide aperture in a micropillar structure are demonstrated. After each oxidation step the con?fined optical modes are analyzed at room temperature. Three regimes are identi?fied. First, the optical con?finement increases when the aperture oxidizes towards the center. Then, the cavity modes shift by more than 30 nm, when the taper starts to oxidize through the center, leading to a decrease in the optical path length. Finally, the resonance frequency levels o?f, when the aperture is oxidized all the way through the micropillar, but confi?ned optical modes with a high quality factor remain. This repetitive oxidation technique therefore enables precise control of the optical cavity volume or wavelength.

  20. Cavity quantum electrodynamics with Anderson-localized modes.

    Science.gov (United States)

    Sapienza, Luca; Thyrrestrup, Henri; Stobbe, Søren; Garcia, Pedro David; Smolka, Stephan; Lodahl, Peter

    2010-03-12

    A major challenge in quantum optics and quantum information technology is to enhance the interaction between single photons and single quantum emitters. This requires highly engineered optical cavities that are inherently sensitive to fabrication imperfections. We have demonstrated a fundamentally different approach in which disorder is used as a resource rather than a nuisance. We generated strongly confined Anderson-localized cavity modes by deliberately adding disorder to photonic crystal waveguides. The emission rate of a semiconductor quantum dot embedded in the waveguide was enhanced by a factor of 15 on resonance with the Anderson-localized mode, and 94% of the emitted single photons coupled to the mode. Disordered photonic media thus provide an efficient platform for quantum electrodynamics, offering an approach to inherently disorder-robust quantum information devices.

  1. Optical cavity cooling of mechanical modes of a semiconductor nanomembrane

    DEFF Research Database (Denmark)

    Usami, Koji; Naesby, A.; Bagci, Tolga

    2012-01-01

    . The resultant photo-induced rigidity is large and a mode temperature cooled from room temperature down to 4 K is realized with 50 μW of light and a cavity finesse of just 10. Thermal stress due to non-radiative relaxation of the electron–hole pairs is the primary cause of the cooling. We also analyse...... an alternative cooling mechanism that is a result of electronic stress via the deformation potential, and outline future directions for cavity optomechanics with optically active semiconductors.......-quality-factor and optically active semiconductor nanomembrane. The cooling is a result of electron–hole generation by cavity photons. Consequently, the cooling factor depends on the optical wavelength, varies drastically in the vicinity of the semiconductor bandgap, and follows the excitonic absorption behaviour...

  2. Higher order mode analysis of the SPL cavities

    CERN Document Server

    Schuh, M; Tuckmantel, J; Welsch, CP

    2010-01-01

    Higher Order Modes (HOMs) can severely limit the operation of superconducting cavities in a linac with high beam current, high duty factor and complex pulse structure. The full HOM spectrum has to be analyzed in order to identify potentially dangerous modes already during the design phase and to define their damping requirements. For this purpose a dedicated beam simulation code focused on beam-HOMinteraction was developed, taking into account important effects like the HOMfrequency spread, beam input jitter, different chopping patterns, as well as klystron and alignment errors. Here, the code is used to investigate in detail the HOM properties of the cavities foreseen in the Superconducting Proton Linac (SPL) at CERN and their potential to drive beam instabilities. Special attention is given to HOM excitation by chopped pulses with high repetition rate.

  3. Pulse properties of external cavity mode locked semiconductor lasers

    DEFF Research Database (Denmark)

    Mulet, Josep; Kroh, Marcel; Mørk, Jesper

    2006-01-01

    The performance of an external-cavity mode-locked semiconductor laser is investigated both theoretically and experimentally. The optimization analysis focuses on the regimes of stable mode locking and the generation of sub-picosecond optical pulses. We demonstrate stable output pulses down to one...... picosecond duration with more than 30 dB trailing pulse suppression. The limiting factors to the device performance are investigated on the basis of a fully-distributed time-domain model.We find that ultrafast gain dynamics effectively reduce the pulse-shaping strength and inhibit the generation...

  4. Dual cavity modes in photonic microcavity-integrated graphene

    Science.gov (United States)

    Sattari, M.; Pourali, N.; Sadri, B.

    2017-08-01

    The interaction of dual-micro-cavity defect modes in a one-dimensional photonic crystal consisting of graphene layers is studied by using the transfer matrix method. The numerical relation of resonances and splitting condition of them are determined in this structure. Results show that for specific repetition numbers of surrounding and middle cells of the structure, a defect mode is split into two completely separated modes. Also, threshold states for merging the defect modes are determined for different amounts of these parameters. In addition, the transmission coefficients and the Faraday rotation angles of these states are calculated and compared with each other. By calculation of light intensity distribution inside the structure at resonance wavelengths, we present consistent qualitative interpretation of the analytical results. The information achieved by this research can be useful to fabricate a variety of graphene-based photonic systems and magneto-optical integrated devices such as miniaturized isolators and circulators.

  5. Coupling of cavities - the way to impose control over their modes

    DEFF Research Database (Denmark)

    Ivinskaya, Aliaksandra; Lavrinenko, Andrei; Sukhorukov, Andrey A.

    2010-01-01

    In this work, we demonstrate that the compound mode properties of coupled photonic-crystal cavities can depend critically on the interplay of distance between cavities and their longitudinal shifts. Thus the robust control over the cavity modes can be imposed. The simple coupled-mode theory...... that this property will be generic for side-coupled cavity systems irrespectively of the individual cavity design, e.g. point-defect cavities in a photonic crystal or linear cavities in one-dimensional arrays of elements (rods or holes). We report here about the finite-difference frequency-domain method (FDFD...

  6. Commercial mode-locked vertical external cavity surface emitting lasers

    Science.gov (United States)

    Lubeigt, Walter; Bialkowski, Bartlomiej; Lin, Jipeng; Head, C. Robin; Hempler, Nils; Maker, Gareth T.; Malcolm, Graeme P. A.

    2017-02-01

    In recent years, M Squared Lasers have successfully commercialized a range of mode-locked vertical external cavity surface emitting lasers (VECSELs) operating between 920-1050nm and producing picosecond-range pulses with average powers above 1W at pulse repetition frequencies (PRF) of 200MHz. These laser products offer a low-cost, easy-to-use and maintenance-free tool for the growing market of nonlinear microscopy. However, in order to present a credible alternative to ultrafast Ti-sapphire lasers, pulse durations below 200fs are required. In the last year, efforts have been directed to reduce the pulse duration of the Dragonfly laser system to below 200fs with a target average power above 1W at a PRF of 200MHz. This paper will describe and discuss the latest efforts undertaken to approach these targets in a laser system operating at 990nm. The relatively low PRF operation of Dragonfly lasers represents a challenging requirement for mode-locked VECSELs due to the very short upper state carrier lifetime, on the order of a few nanoseconds, which can lead to double pulsing behavior in longer cavities as the time between consecutive pulses is increased. Most notably, the design of the Dragonfly VECSEL cavity was considerably modified and the laser system extended with a nonlinear pulse stretcher and an additional compression stage. The improved Dragonfly laser system achieved pulse duration as short as 130fs with an average power of 0.85W.

  7. Comb mode filtering silver mirror cavity for spectroscopic distance measurement

    Science.gov (United States)

    Šmíd, R.; Hänsel, A.; Pravdová, L.; Sobota, J.; Číp, O.; Bhattacharya, N.

    2016-09-01

    In this work we present a design of an external optical cavity based on Fabry-Perot etalons applied to a 100 MHz Er-doped fiber optical frequency comb working at 1560 nm to increase its repetition frequency. A Fabry-Perot cavity is constructed based on a transportable cage system with two silver mirrors in plano-concave geometry including the mode-matching lenses, fiber coupled collimation package and detection unit. The system enables full 3D angle mirror tilting and x-y off axis movement as well as distance between the mirrors. We demonstrate the increase of repetition frequency by direct measurement of the beat frequency and spectrally by using the virtually imaged phased array images.

  8. Goldstone and Higgs modes of photons inside a cavity.

    Science.gov (United States)

    Yi-Xiang, Yu; Ye, Jinwu; Liu, Wu-Ming

    2013-12-11

    Goldstone and Higgs modes have been detected in various condensed matter, cold atom and particle physics experiments. Here, we demonstrate that the two modes can also be observed in optical systems with only a few (artificial) atoms inside a cavity. We establish this connection by studying the U(1)/Z2 Dicke model where N qubits (atoms) coupled to a single photon mode. We determine the Goldstone and Higgs modes inside the super-radiant phase and their corresponding spectral weights by performing both 1/J = 2/N expansion and exact diagonalization (ED) study at a finite N. We find nearly perfect agreements between the results achieved by the two approaches when N gets down even to N = 2. The quantum finite size effects at a few qubits make the two modes quite robust against an effectively small counterrotating wave term. We present a few schemes to reduce the critical coupling strength, so the two modes can be observed in several current available experimental systems by just conventional optical measurements.

  9. Generation of SU(2) Coherent States for a Cavity Mode and a Collective Atomic Mode

    Institute of Scientific and Technical Information of China (English)

    ZHENG Shi-Biao

    2009-01-01

    We propose a scheme for generation of SU(2) coherent states for an atomic ensemble and a cavity mode. In the scheme a collection of two-level atoms resonantly interact with a single-mode quantized field. Under certain conditions, the system can evolve from a Fock state to a highly entangled SU(2) coherent state. The operation speed increases as the number of atoms increases, which is important in view of decoherence.

  10. Effects of mode degeneracy in the LIGO Livingston Observatory recycling cavity

    CERN Document Server

    Gretarsson, Andri M; Frolov, Valery; O'Reilly, Brian; Fritschel, Peter K

    2007-01-01

    We analyze the electromagnetic fields in a Pound-Drever-Hall locked, marginally unstable, Fabry-Perot cavity as a function of small changes in the cavity length during resonance. More specifically, we compare the results of a detailed numerical model with the behavior of the recycling cavity of the Laser Interferometer Gravitational-wave Observatory (LIGO) detector that is located in Livingston, Louisiana. In the interferometer's normal mode of operation, the recycling cavity is stabilized by inducing a thermal lens in the cavity mirrors with an external CO2 laser. During the study described here, this thermal compensation system was not operating, causing the cavity to be marginally optically unstable and cavity modes to become degenerate. In contrast to stable optical cavities, the modal content of the resonating beam in the uncompensated recycling cavity is significantly altered by very small cavity length changes. This modifies the error signals used to control the cavity length in such a way that the zer...

  11. Optothermal transport behavior in whispering gallery mode optical cavities

    Energy Technology Data Exchange (ETDEWEB)

    Soltani, Soheil [Ming Hsieh Department of Electrical Engineering-Electrophysics, University of Southern California, Los Angeles, California 90089 (United States); Armani, Andrea M., E-mail: armani@usc.edu [Ming Hsieh Department of Electrical Engineering-Electrophysics, University of Southern California, Los Angeles, California 90089 (United States); Mork Family Department of Chemical Engineering and Materials Science, University of Southern California, Los Angeles, California 90089 (United States)

    2014-08-04

    Over the past century, whispering gallery mode optical cavities have enabled numerous advances in science and engineering, such as discoveries in quantum mechanics and non-linear optics, as well as the development of optical gyroscopes and add drop filters. One reason for their widespread appeal is their ability to confine light for long periods of time, resulting in high circulating intensities. However, when sufficiently large amounts of optical power are coupled into these cavities, they begin to experience optothermal or photothermal behavior, in which the optical energy is converted into heat. Above the optothermal threshold, the resonance behavior is no longer solely defined by electromagnetics. Previous work has primarily focused on the role of the optothermal coefficient of the material in this instability. However, the physics of this optothermal behavior is significantly more complex. In the present work, we develop a predictive theory based on a generalizable analytical expression in combination with a geometry-specific COMSOL Multiphysics finite element method model. The simulation couples the optical and thermal physics components, accounting for geometry variations as well as the temporal and spatial profile of the optical field. To experimentally verify our theoretical model, the optothermal thresholds of a series of silica toroidal resonant cavities are characterized at different wavelengths (visible through near-infrared) and using different device geometries. The silica toroid offers a particularly rigorous case study for the developed optothermal model because of its complex geometrical structure which provides multiple thermal transport paths.

  12. Paired modes of heterostructure cavities in photonic crystal waveguides with split band edges

    DEFF Research Database (Denmark)

    Mahmoodian, Sahand; Sukhorukov, Andrey A.; Ha, Sangwoo

    2010-01-01

    We investigate the modes of double heterostructure cavities where the underlying photonic crystal waveguide has been dispersion engineered to have two band-edges inside the Brillouin zone. By deriving and using a perturbative method, we show that these structures possess two modes. For unapodized...... cavities, the relative detuning of the two modes can be controlled by changing the cavity length, and for particular lengths, a resonant-like effect makes the modes degenerate. For apodized cavities no such resonances exist and the modes are always non-degenerate....

  13. Engineering three-dimensional maximally entangled states for two modes in a bimodal cavity

    Institute of Scientific and Technical Information of China (English)

    Yang Zhen-Biao; Su Wan-Jun

    2007-01-01

    An alternative scheme is proposed for engineering three-dimensional maximally entangled states for two modes of a superconducting microwave cavity. In this scheme, an appropriately prepared four-level atom is sent through a bimodal cavity. During its passing through the cavity, the atom is coupled resonantly with two cavity modes simultaneously and addressed by a classical microwave pulse tuned to the required transition. Then the atomic states are detected to collapse two modes onto a three-dimensional maximally entangled state. The scheme is different from the previous one in which two nonlocal cavities are used. A comparison between them is also made.

  14. Off-resonance coupling between a cavity mode and an ensemble of driven spins

    Science.gov (United States)

    Wang, Hui; Masis, Sergei; Levi, Roei; Shtempluk, Oleg; Buks, Eyal

    2017-05-01

    We study the interaction between a superconducting cavity and a spin ensemble. The response of a cavity mode is monitored while simultaneously the spins are driven at a frequency close to their Larmor frequency, which is tuned to a value much higher than the cavity resonance. We experimentally find that the effective damping rate of the cavity mode is shifted by the driven spins. The measured shift in the damping rate is attributed to the retarded response of the cavity mode to the driven spins. The experimental results are compared with theoretical predictions and fair agreement is found.

  15. Discovery of higher order modes in a cylindrical reentrant-ring cavity resonator

    CERN Document Server

    Fan, Y; Carvalho, N C; Floch, J-M Le; Shan, Q; Tobar, M E

    2013-01-01

    Rigorous analysis of the properties of resonant modes in a reentrant cavity structure comprising of a post and ring is undertaken and verified experimentally. In particular for the first time we show the existence of higher order reentrant cavity modes in such a structure. Results show this cavity has a better displacement sensitivity compared to the common fundamental mode in a reentrant cylindrical cavity with just a single post. Thus, this type of cavity has the potential to operate as a highly sensitive transducer for a variety of precision measurement applications.

  16. Piezo activated mode tracking system for widely tunable mode-hop-free external cavity mid-IR semiconductor lasers

    Science.gov (United States)

    Wysocki, Gerard (Inventor); Tittel, Frank K. (Inventor); Curl, Robert F. (Inventor)

    2010-01-01

    A widely tunable, mode-hop-free semiconductor laser operating in the mid-IR comprises a QCL laser chip having an effective QCL cavity length, a diffraction grating defining a grating angle and an external cavity length with respect to said chip, and means for controlling the QCL cavity length, the external cavity length, and the grating angle. The laser of claim 1 wherein said chip may be tuned over a range of frequencies even in the absence of an anti-reflective coating. The diffraction grating is controllably pivotable and translatable relative to said chip and the effective QCL cavity length can be adjusted by varying the injection current to the chip. The laser can be used for high resolution spectroscopic applications and multi species trace-gas detection. Mode-hopping is avoided by controlling the effective QCL cavity length, the external cavity length, and the grating angle so as to replicate a virtual pivot point.

  17. Analysis of small deflection touch mode behavior in capacitive pressure sensors

    DEFF Research Database (Denmark)

    Fragiacomo, Giulio; Ansbæk, Thor; Pedersen, Thomas;

    2010-01-01

    mode), touch point pressure and parasitic capacitance. Therefore, the desired device can be designed without using finite element modeling (FEM). This reduces the effort needed to design a micromachined TMCPS. Finally, the model has been compared with a micromachined TMCPS showing an excellent...... such that geometrical scalings are revealed. We show that, in the case of linear elastic behavior, a simple analytical model can be found for a touch mode capacitive pressure sensor (TMCPS). With this model it is possible to readily evaluate the main features of a TMCPS such as: sensitivity (both in normal and touch...

  18. Higher Order Mode (HOM) Impedance and Damping Study for the LHC Capture Cavity

    CERN Document Server

    Linnecar, Trevor Paul R; Tückmantel, Joachim; CERN. Geneva. SPS and LHC Division

    2001-01-01

    To investigate the higher order mode, HOM, damping in the LHC 200MHz ACN cavity when using four HOM couplers, simulations have been done by both 3-D frequency domain and time domain methods. These simulations have previously been used in other studies of HOM damped cavities and shown to be effective by comparing measurement and simulation results[1] [2]. Using these methods the impedance spectrum of the HOM modes in the cavity before and after damping has been obtained. From this, detailed information about the HOM coupler's contribution to HOM damping can be obtained. The distribution and magnitude of some potentially dangerous HOM modes in the ACN cavity have been found.

  19. Intensity Tuning in Single Mode Microchip Nd:YAG Laser with External Cavity

    Institute of Scientific and Technical Information of China (English)

    TAN Yi-Dong; ZHANG Shu-Lian

    2006-01-01

    We investigate the characteristics of intensity tuning in a single mode microchip Nd:YAG laser with an external cavity. The undulation of laser intensity in a period of λ/2 change of the internal cavity length is observed.Two different optical feedback cases are performed. One is an external cavity reflector perfectly aligned and the other is an external cavity reflector tilted. However, the fluctuation frequency of laser intensity in a period of λ/2 change of the internal cavity length in these two cases is found to be determined by the ratio of external cavity length to internal cavity length. Meanwhile, for the tilted external cavity, the fluctuation frequency is also related to multiple feedbacks in the tilted external cavity.

  20. Selection of a LGp0-shaped fundamental mode in a laser cavity: Phase versus amplitude masks

    CSIR Research Space (South Africa)

    Hasnaoui, A

    2012-01-01

    Full Text Available Laser beams of a single high-order transverse mode have been of interest to the laser community for several years now. In order to achieve such a mode as the fundamental mode of the cavity, mode selecting elements in the form of a phase or amplitude...

  1. Studies on high order mode of bell-shaped prototype cavities

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Aluminium and copper prototype cavities were designed to study higher order modes(HOM).An automatic field mapping system was developed with LabVIEW to measure the adiofrequency(RF)charac teristics,such as resonant frequency,Q-value,shunt impedance and electromagnetic field distribution of the higher-order modes in a model RF cavity.Two kinds of the bell-shaped cavities were measured using the field mapping system,their frequencies are 1.5 GHz and 800 MHz respectively.The fields' distributions of the monopole modes and dipole modes,as well the R/Q values,were measured.

  2. Higher order modes HOMs in coupled cavities of the FLASH module ACC39

    CERN Document Server

    Shinton, I R R; Li, Z; Zhang, P

    2011-01-01

    We analyse the higher order modes (HOM’s) in the 3.9GHz bunch shaping cavities installed in the FLASH facility at DESY. A suite of finite element computer codes (including HFSS and ACE3P) and globalised scattering matrix calculations (GSM) are used to investigate the modes in these cavities. This study is primarily focused on the dipole component of the multiband expansion of the wakefield, with the emphasis being on the development of a HOM-based BPM system for ACC39. Coupled inter-cavity modes are simulated together with a limited band of trapped modes.

  3. Higher Order Modes in Coupled Cavities of the Flash Module ACC39

    CERN Document Server

    Shinton, I R R; Li, Z; Zhang, P

    2011-01-01

    We analyse the higher order modes (HOM's) in the 3.9GHz bunch shaping cavities installed in the FLASH facility at DESY. A suite of finite element computer codes (including HFSS and ACE3P) and globalised scattering matrix calculations (GSM) are used to investigate the modes in these cavities. This study is primarily focused on the dipole component of the multiband expansion of the wakefield, with the emphasis being on the development of a HOM-based BPM system for ACC39. Coupled inter-cavity modes are simulated together with a limited band of trapped modes.

  4. Higher Order Modes in Third Harmonic Cavities for XFEL/FLASH

    Energy Technology Data Exchange (ETDEWEB)

    Shinton, I.R.R.; /Manchester U. /Cockcroft Inst. Accel. Sci. Tech.; Baboi, N.; /DESY; Eddy, N.; /Fermilab; Flisgen, T.; Glock, H.W.; /Rostock U.; Jones, R.M.; Juntong, N.; /Manchester U. /DESY; Khabiboulline, T.N.; /Fermilab; van Rienen, U; /Rostock U.; Zhang, P.; /Manchester U. /DESY /Cockcroft Inst. Accel. Sci. Tech.

    2010-06-01

    We analyse higher order modes in the 3.9 GHz bunch shaping cavities recently installed in the FLASH facility at DESY. We report on recent experimental results on the frequency spectrum from probe based measurements made at CMTB at DESY. These are compared to those predicted by finite difference and finite element computer codes. This study is focused mainly on the dipole component of the multi-pole expansion of the wakefield. The modes are readily identifiable as single-cavity modes provided the frequencies of these modes are below the cut-off of the inter-connecting beam pipes. The modes above cut-off are coupled to the 4 cavities and are distinct from single cavity modes.

  5. Cavity mode control in side-coupled periodic waveguides: theory and experiment

    DEFF Research Database (Denmark)

    Ha, Sangwoo; Sukhorukov, A.; Lavrinenko, Andrei

    2010-01-01

    as the cavities are brought closer. We show that the longitudinal shift enables flexible control over the fundamental modes, whose frequency detuning can be reduced down to zero. Our coupled-mode theory analysis reveals an intrinsic link between the mode tuning and the transformation of slow-light dispersion...... at the photonic band-edge.We illustrate our approach through numerical modeling of cavities created in arrays of dielectric rods, and confirm our predictions with experimental observations....

  6. Dual-cavity Nd:YAG laser with Laguerre-Gaussian (LG0n) mode output

    Science.gov (United States)

    Kim, D. J.; Kim, J. W.

    2017-01-01

    Direct excitation of an arbitrary Laguerre-Gaussian (LG0n) mode with helical wavefronts in a diode-end-pumped solid state laser employing a dual-cavity configuration is reported. Through simple adjustments of the intra-cavity apertures in the dual-cavity laser configuration, the spatial gain distribution and the cavity loss could be optimized for the targeted LG0 n mode. This approach has been applied to a diode-pumped Nd: YAG laser to achieve selective lasing of the LG01, LG02, and LG03 modes. Also, an optical vortex laser beam was produced directly from the laser resonator by determining the wavefront handedness of each LG mode output using an intra-cavity etalon. The prospects of further power scaling and laser performance improvements will be discussed.

  7. III-nitride tunable cup-cavities supporting quasi whispering gallery modes from ultraviolet to infrared

    Science.gov (United States)

    Shubina, T. V.; Pozina, G.; Jmerik, V. N.; Davydov, V. Yu.; Hemmingsson, C.; Andrianov, A. V.; Kazanov, D. R.; Ivanov, S. V.

    2015-12-01

    Rapidly developing nanophotonics needs microresonators for different spectral ranges, formed by chip-compatible technologies. In addition, the tunable ones are much in demand. Here, we present site-controlled III-nitride monocrystal cup-cavities grown by molecular beam epitaxy. The cup-cavities can operate from ultraviolet to near-infrared, supporting quasi whispering gallery modes up to room temperature. Besides, their energies are identical in large ’ripened’ crystals. In these cavities, the refractive index variation near an absorption edge causes the remarkable effect of mode switching, which is accompanied by the spatial redistribution of electric field intensity with concentration of light into a subwavelength volume. Our results shed light on the mode behavior in semiconductor cavities and open the way for single-growth-run manufacturing the devices comprising an active region and a cavity with tunable mode frequencies.

  8. Quantum Statistical Properties of the Exciton in a Leaky Quasi-Mode Cavity

    Institute of Scientific and Technical Information of China (English)

    YU Zhao-Xian; JIAO Zhi-Yong

    2002-01-01

    We have studied quantum statistical properties of the exciton in a leaky quasi-mode cavity. It is shown that when the exciton is initially in a squeezed coherent state whereas cavity initially in a vacuum state, there is energy exchange between the exciton and cavity. Both the exciton and cavity may exhibit sub-Poissonian distribution and exist quadrature squeezing. Calculation shows that correlation between the exciton and cavity is classical, which implies that there is not the violation of the Cauchy-Schwartz inequality.

  9. Cavity-enhanced ultrafast two-dimensional spectroscopy using higher order modes

    Science.gov (United States)

    Allison, Thomas K.

    2017-02-01

    We describe methods using frequency combs and optical resonators for recording two-dimensional (2D) ultrafast spectroscopy signals with high sensitivity. By coupling multiple frequency combs to higher-order modes of one or more optical cavities, background-free, cavity-enhanced 2D spectroscopy signals are naturally generated via phase cycling. As in cavity-enhanced ultrafast transient absorption spectroscopy, the signal to noise is enhanced by a factor proportional to the cavity finesse squared, so even using cavities of modest finesse, a very high sensitivity is expected, enabling ultrafast 2D spectroscopy experiments in dilute molecular beams.

  10. Cavity-enhanced ultrafast two-dimensional spectroscopy using higher-order modes

    CERN Document Server

    Allison, Thomas K

    2016-01-01

    We describe methods using frequency combs and optical resonators for recording two-dimensional (2D) ultrafast spectroscopy signals with high sensitivity. By coupling multiple frequency combs to higher-order modes of one or more optical cavities, background-free, cavity-enhanced 2D spectroscopy signals are naturally generated via phase cycling. As in cavity-enhanced ultrafast transient absorption spectroscopy (CE-TAS), the signal to noise is enhanced by a factor proportional to the cavity finesse squared, so even using cavities of modest finesse, a very high sensitivity is expected, enabling ultrafast 2D spectroscopy experiments in dilute molecular beams.

  11. Systematization of All Resonance Modes in Circular Dielectric Cavities

    NARCIS (Netherlands)

    Dettmann, C.P.; Morozov, G.V.; Sieber, M.; Waalkens, H.

    2009-01-01

    Circular dielectric cavities are key components for the construction of optic microresonators and microlasers. They are one of very few cases where the transcendental equations for complex eigenmodes (resonances) of an open system (dielectric cavity) can be found analytically in an exact manner. The

  12. Nonradiating and radiating modes excited by quantum emitters in open epsilon-near-zero cavities

    CERN Document Server

    Liberal, Iñigo

    2015-01-01

    Controlling the emission and interaction properties of quantum emitters (QEs) embedded within an optical cavity is a key technique in engineering light-matter interactions at the nanoscale, as well as in the development of quantum information processing. State-of-the-art optical cavities are based on high Q photonics crystals and dielectric resonators. However, wealthier responses might be attainable with cavities carved in more exotic materials. Here, we theoretically investigate the emission and interaction properties of QEs embedded in open epsilon-near-zero (ENZ) cavities. Using analytical methods and numerical simulations, it is demonstrated that open ENZ cavities present the unique property of supporting nonradiating modes independently of the geometry of the external boundary of the cavity (shape, size, topology...). Moreover, the possibility of switching between radiating and nonradiating modes enables a dynamic control of both the emission by, and the interaction between, QEs. These phenomena provide...

  13. Mode-locking external-cavity laser-diode sensor for displacement measurements of technical surfaces

    Science.gov (United States)

    Czarske, Jürgen; Möbius, Jasper; Moldenhauer, Karsten

    2005-09-01

    A novel laser sensor for position measurements of technical solid-state surfaces is proposed. An external Fabry-Perot laser cavity is assembled by use of an antireflection-coated laser diode together with the technical surface. Mode locking results from pumping the laser diode synchronously to the mode spacing of the cavity. The laser cavity length, i.e., the distance to the measurement object, is determined by evaluation of the modulation transfer function of the cavity by means of a phase-locked loop. The mode-locking external-cavity laser sensor incorporates a resonance effect that results in highly resolving position and displacement measurements. More than a factor-of-10 higher resolution than with conventional nonresonant sensing principles is achieved. Results of the displacement measurements of various technical surfaces are reported. Experimental and theoretical investigations are in good agreement.

  14. A Bloch modal approach for engineering waveguide and cavity modes in two-dimensional photonic crystals

    DEFF Research Database (Denmark)

    de Lasson, Jakob Rosenkrantz; Kristensen, Philip Trøst; Mørk, Jesper;

    2014-01-01

    uses no external excitation and determines the quasi-normal modes as unity eigenvalues of the cavity roundtrip matrix. We demonstrate the method and the quasi-normal modes for two types of two-dimensional photonic crystal structures, and discuss the quasi-normal mode eld distributions and Q...

  15. Observations of a Pc5 global (cavity/waveguide) mode outside the plasmasphere by THEMIS

    DEFF Research Database (Denmark)

    Hartinger, Michael; Angelopoulos, Vassilis; Moldwin, Mark B.

    2012-01-01

    Standing fast mode waves known as global modes, or cavity/waveguide modes, have been extensively studied as a potential driver of monochromatic shear Alfven waves in the Earth's magnetosphere via the field line resonance (FLR) mechanism. However, their existence outside of the plasmasphere remain...

  16. Mode-locked Pr3+-doped silica fiber laser with an external cavity

    DEFF Research Database (Denmark)

    Shi, Yuan; Poulsen, Christian; Sejka, Milan

    1994-01-01

    We present a Pr3+-doped silica-based fiber laser mode-locked by using a linear external cavity with a vibrating mirror. Stable laser pulses with a FWHM of less than 44 ps, peak power greater than 9 W, and repetition rate up to 100 MHz are obtained. The pulse width versus cavity mismatch ΔL and pump...

  17. Digital control of laser modes with an intra-cavity spatial light modulator

    CSIR Research Space (South Africa)

    Ngcobo, S

    2014-02-01

    Full Text Available In this paper we outline a simple laser cavity which produces customised on-demand digitally controlled laser modes by replacing the end-mirror of the cavity with an electrically addressed reflective phase-only spatial light modulator as a digital...

  18. Hybridization of photon-plasmon modes in metal-coated microtubular cavities

    CERN Document Server

    Yin, Yin; Engemaier, Vivienne; Giudicatti, Silvia; Naz, Ehsan Saei Ghareh; Ma, Libo; Schmidt, Oliver G

    2016-01-01

    The coupling of resonant light and surface plasmons in metal layer coated optical microcavities results in the formation of hybrid photon-plasmon modes. Here, we comprehensively investigate the hybridization mechanism of photon-plasmon modes based on opto-plasmonic microtubular cavities. By changing the cavity structure and the metal layer thickness, weakly, moderately and strongly hybridized resonant modes are demonstrated depending on the photon-plasmon coupling strength. An effective potential approach is applied to illustrate the hybridization of photon-plasmon modes relying on the competition between light confinement by the cavity wall and the potential barrier introduced by the metal layer. Our work reveals the basic physical mechanisms for the generation of hybrid modes in metal-coated whispering-gallery-mode microcavities, and is of importance for the study of enhanced light-matter interactions and potential sensing applications.

  19. Normal mode splitting and mechanical effects of an optical lattice in a ring cavity

    CERN Document Server

    Klinner, J; Lindholdt, M; Nagorny, B; Hemmerich, Andreas; Klinner, Julian; Lindholdt, Malik; Nagorny, Boris

    2005-01-01

    A novel regime of atom-cavity physics is explored, arising when large atom samples dispersively interact with high-finesse optical cavities. A stable far detuned optical lattice of several million rubidium atoms is formed inside an optical ring resonator by coupling equal amounts of laser light to each propagation direction of a longitudinal cavity mode. An adjacent longitudinal mode, detunedby about 3 GHz, is used to perform probe transmission spectroscopy of the system. The atom-cavity coupling for the lattice beams and the probe is dispersive and dissipation results only from the finite photon-storage time. The observation of two well-resolved normal modes demonstrates the regime of strong cooperative coupling. The details of the normal mode spectrum reveal mechanical effects associated with the retroaction of the probe upon the optical lattice.

  20. Normal Mode Splitting and Mechanical Effects of an Optical Lattice in a Ring Cavity

    Science.gov (United States)

    Klinner, Julian; Lindholdt, Malik; Nagorny, Boris; Hemmerich, Andreas

    2006-01-01

    A novel regime of atom-cavity physics is explored, arising when large atom samples dispersively interact with high-finesse optical cavities. A stable far-detuned optical lattice of several million rubidium atoms is formed inside an optical ring resonator by coupling equal amounts of laser light to each propagation direction of a longitudinal cavity mode. An adjacent longitudinal mode, detuned by about 3 GHz, is used to perform probe transmission spectroscopy of the system. The atom-cavity coupling for the lattice beams and the probe is dispersive and dissipation results only from the finite photon-storage time. The observation of two well-resolved normal modes demonstrates the regime of strong cooperative coupling. The details of the normal mode spectrum reveal mechanical effects associated with the retroaction of the probe upon the optical lattice.

  1. Visualization of the Mode Shapes of Pressure Oscillation in a Cylindrical Cavity

    Energy Technology Data Exchange (ETDEWEB)

    He, Xin [Tsinghua Univ., Beijing (China); Qi, Yunliang [Tsinghua Univ., Beijing (China); Wang, Zhi [Tsinghua Univ., Beijing (China); Wang, Jianxin [Tsinghua Univ., Beijing (China); Shuai, Shijin [Tsinghua Univ., Beijing (China); Tao, Ling [National Renewable Energy Lab. (NREL), Golden, CO (United States)

    2015-06-08

    Our work describes a novel experimental method to visualize the mode shapes of pressure oscillation in a cylindrical cavity. Acoustic resonance in a cavity is a grand old problem that has been under investigation (using both analytical and numerical methods) for more than a century. In this article, a novel method based on high speed imaging of combustion chemiluminescence was presented to visualize the mode shapes of pressure oscillation in a cylindrical cavity. By generating high-temperature combustion gases and strong pressure waves simultaneously in a cylindrical cavity, the pressure oscillation can be inferred due to the chemiluminescence emissions of the combustion products. We can then visualized the mode shapes by reconstructing the images based on the amplitudes of the luminosity spectrum at the corresponding resonant frequencies. Up to 11 resonant mode shapes were clearly visualized, each matching very well with the analytical solutions.

  2. Coherent coupling of molecular resonators with a micro-cavity mode

    CERN Document Server

    Shalabney, Atef; Hutchison, James A; Pupillo, Guido; Genet, Cyriaque; Ebbesen, Thomas W

    2014-01-01

    Strong coupling is at the heart of optomechanics where it enables coherent quantum state transfer between light and micromechanical oscillators. Strongly coupled molecule-cavity systems have also revealed unique properties enabling even the control of chemical rates through the optical hybridization of the electronic states. Here we combine these notions to show that molecular vibrational modes of the electronic ground state can be coherently coupled with a micro-cavity mode at room temperature, given the low vibrational thermal occupation factors n_{\

  3. Spatial mode effects in a cavity EIT-based quantum memory with ion Coulomb crystals

    CERN Document Server

    Zangenberg, Kasper R; Drewsen, Michael

    2012-01-01

    Quantum storage and retrieval of light in ion Coulomb crystals using cavity electromagnetically induced transparency is investigated theoretically. It is found that, when both the control and probe fields are coupled to the same cavity mode, their transverse mode profile affects the quantum memory efficiency in a non-trivial way. Under such conditions the control field parameters and crystal dimensions that maximize the memory efficiency are calculated.

  4. Spatial mode effects in a cavity-EIT based quantum memory with ion Coulomb crystals

    DEFF Research Database (Denmark)

    Zangenberg, Kasper Rothe; Dantan, Aurelien Romain; Drewsen, Michael

    2012-01-01

    Quantum storage and retrieval of light in ion Coulomb crystals using cavity electromagnetically induced transparency are investigated theoretically. It is found that when both the control and the probe fields are coupled to the same spatial cavity mode, their transverse mode profile affects the q...... the quantum memory efficiency in a non-trivial way. Under such conditions, the control-field parameters and crystal dimensions that maximize the memory efficiency are calculated....

  5. Measuring the Wigner Functions of Two-Mode Cavity Fields and Testing the Bell's Inequalities

    Institute of Scientific and Technical Information of China (English)

    张智明

    2004-01-01

    We propose a scheme for measuring the Wigner function of a two-mode cavity field. The scheme bases on the interaction between the two-mode cavity field and three-level atoms. We find a simple relation between the Wigner function and the atomic population. One can obtain the Wigner function by measuring the atomic population with a micromaser-like experiment and doing a numerical integral. By using the two-mode Wigner function one can obtain the Clauser-Horne combination and test the Bell's inequalities. We test our equations with a two-mode entanglement state and the results are rather good.

  6. Active lower order mode damping for the four rod LHC crab cavity

    Science.gov (United States)

    Dexter, A. C.; Burt, G.; Apsimon, R.

    2017-02-01

    The high luminosity upgrade planned for the LHC requires crab cavities to rotate bunches into alignment at the interaction points. They compensate for a crossing angle near 500 μ r ad . It is anticipated that four crab cavities in succession will be utilized to achieve this rotation on either side of each IP in a local crossing scheme. A crab cavity operates in a dipole mode but always has an accelerating mode that may be above or below the frequency of the operating mode. Crab cavities are given couplers to ensure that unwanted acceleration modes are strongly damped however employing standard practice these unwanted modes will always have some level of excitation. Where this excitation has a random phase it might promote bunch growth and limit beam lifetime. This paper sets out a method for active control of the phase and amplitude of the unwanted lowest accelerating mode in the crab cavities. The paper investigates the level of suppression that can be achieved as a function cavity quality factor and proximity to resonance.

  7. Mode-locked pulse oscillation of a self-resonating enhancement optical cavity

    CERN Document Server

    Hosaka, Yuji; Kosuge, Atsushi; Omori, Tsunehiko; Sakaue, Kazuyuki; Takahashi, Tohru; Uesugi, Yuuki; Urakawa, Junji; Washio, Masakazu

    2016-01-01

    A power enhancement optical cavity is a compelling means of realizing a pulsed laser with a high peak power and a high repetition frequency, which is not feasible by using a simple amplifier scheme. However, a precise feedback system is necessary for maintaining the narrow resonance condition of the optical cavity, and has become a major technical issue in developing such cavities. We developed a new approach that does not require any active feedback system, by placing the cavity in the outer loop of a laser amplifier. We report on the first demonstration of a mode-locked pulse oscillation using the new system.

  8. Deterministic coupling of a system of multiple quantum dots to a single photonic cavity mode

    Science.gov (United States)

    Lyasota, A.; Jarlov, C.; Gallo, P.; Rudra, A.; Dwir, B.; Kapon, E.

    2017-07-01

    We fabricated and studied a system comprising four site-controlled semiconductor quantum dots (QDs) embedded in a linear photonic crystal membrane cavity. The excellent position control and small spectral broadening permit coupling of the emission of all four QDs to the same photonic cavity modes. This is corroborated by co-polarization of the QD and cavity emission lines, as well as reduction in decay time, both with characteristic dependence on QD-cavity energy detuning. Scaling up to larger QD systems is discussed.

  9. A Q-switched, mode-locked fiber laser employing subharmonic cavity modulation.

    Science.gov (United States)

    Chang, You Min; Lee, Junsu; Lee, Ju Han

    2011-12-19

    We present a new and simple approach for the generation of Q-switched, mode-locked pulses from a laser cavity. The approach is based on cavity loss modulation that employs a subharmonic frequency of the fundamental intermode frequency spacing. A range of experiments have been carried out using an erbium-doped fiber-based ring cavity laser in order to verify that this simple approach can readily produce high quality Q-switched, mode-locked pulses. An active tuning of the Q-switched envelope repetition rate is also shown to be easily achievable by adjusting the order of the applied subharmonic frequency.

  10. Phonon interaction with coupled photonic-plasmonic modes in a phoxonic cavity

    Directory of Open Access Journals (Sweden)

    S. El-Jallal

    2016-12-01

    Full Text Available We present a theoretical investigation of the acousto-optic interaction in a two-dimensional phoxonic crystal cavity containing a metallic nanowire. The crystal is constituted by a square array of cylindrical holes in a TiO2 matrix containing a cavity inside which a gold nanowire is introduced. The optical modes of the cavity are therefore of combined photonic-plasmonic character. We calculate the strength of coupling between these modes and the localized phonons of the cavity, based on the “Moving Interface” mechanism of acousto-optic coupling. We discuss the coupling strength as a function of the size and position of the metallic nanowire and compare the results with those of a cavity without metallic particle.

  11. Development of superconducting crossbar-H-mode cavities for proton and ion accelerators

    Directory of Open Access Journals (Sweden)

    F. Dziuba

    2010-04-01

    Full Text Available The crossbar-H-mode (CH structure is the first superconducting multicell drift tube cavity for the low and medium energy range operated in the H_{21} mode. Because of the large energy gain per cavity, which leads to high real estate gradients, it is an excellent candidate for the efficient acceleration in high power proton and ion accelerators with fixed velocity profile. A prototype cavity has been developed and tested successfully with a gradient of 7  MV/m. A few new superconducting CH cavities with improved geometries for different high power applications are under development at present. One cavity (f=325  MHz, β=0.16, seven cells is currently under construction and studied with respect to a possible upgrade option for the GSI UNILAC. Another cavity (f=217  MHz, β=0.059, 15 cells is designed for a cw operated energy variable heavy ion linac application. Furthermore, the EUROTRANS project (European research program for the transmutation of high level nuclear waste in an accelerator driven system, 600 MeV protons, 352 MHz is one of many possible applications for this kind of superconducting rf cavity. In this context a layout of the 17 MeV EUROTRANS injector containing four superconducting CH cavities was proposed by the Institute for Applied Physics (IAP Frankfurt. The status of the cavity development related to the EUROTRANS injector is presented.

  12. Analysis of a Triple-cavity Photonic Molecule Based on Coupled Mode Theory

    CERN Document Server

    Yang, Chao; Jiang, Xiaoshun; Xiao, Min

    2016-01-01

    In this paper, we analyze a chain-linked triple-cavity photonic molecule (TCPM) with controllable coupling strengths between the cavities on their spectral properties and field (energy) distributions by solving eigenvalues and eigenvectors of the Hamiltonian matrix based on coupled mode theory. Phase transition is extended from double-cavity photonic molecules (DCPMs) to TCPMs, and evolutions of the supermode frequencies and linewidths are analyzed, which have synchronous relations with the degree of coherence between adjacent optical microcavities and energy distributions in the three cavities, respectively. We develop a superposition picture for the three supermodes of the TCPM, as interferences between supermodes of sub-DCPMs. In particular, we demonstrate the abnormal properties of the central supermode in TCPMs, such as dark state in middle cavity and phase shift when energy flowing between side cavities, which are promising in information processing and remote control of energy. General properties of TC...

  13. High Finesse Fiber Fabry-Perot Cavities: Stabilization and Mode Matching Analysis

    CERN Document Server

    Gallego, Jose; Alavi, Seyed Khalil; Alt, Wolfgang; Martinez-Dorantes, Miguel; Meschede, Dieter; Ratschbacher, Lothar

    2015-01-01

    Fiber Fabry-Perot cavities, formed by micro-machined mirrors on the end-facets of optical fibers, are used in an increasing number of technical and scientific applications, where they typically require precise stabilization of their optical resonances. Here, we study two different approaches to construct fiber Fabry-Perot resonators and stabilize their length for experiments in cavity quantum electrodynamics with neutral atoms. A piezo-mechanically actuated cavity with feedback based on the Pound-Drever-Hall locking technique is compared to a novel rigid cavity design that makes use of the high passive stability of a monolithic cavity spacer and employs thermal self-locking and external temperature tuning. Furthermore, we present a general analysis of the mode matching problem in fiber Fabry-Perot cavities, which explains the asymmetry in their reflective line shapes and has important implications for the optimal alignment of the fiber resonators. Finally, we discuss the issue of fiber-generated background ph...

  14. Selection of lasing direction in single mode semiconductor square ring cavities

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jin-Woong; Kim, Kyoung-Youm; Moon, Hee-Jong; Hyun, Kyung-Sook, E-mail: kshyun@sejong.ac.kr [Department of Optical Engineering, Sejong University, 98 Kunja-Dong, Kwangjin-K, Seoul 143-747 (Korea, Republic of)

    2016-02-07

    We propose and demonstrate a selection scheme of lasing direction by imposing a loss imbalance structure into the single mode square ring cavity. The control of the traveling direction is realized by introducing a taper-step section in one of the straight waveguides of the square ring cavity. It was shown by semi-analytic calculation that the taper-step section in the cavity provides effective loss imbalance between two travelling directions as the round trip repeats. Various kinds of square cavities were fabricated using InGaAsP/InGaAs multiple quantum well semiconductor materials in order to test the direction selectivity while maintaining the single mode. We also measured the pump power dependent lasing spectra to investigate the maintenance property of the lasing direction. The experimental results demonstrated that the proposed scheme is an efficient means for a unidirectional lasing in a single mode laser.

  15. Generalized effective mode volume for leaky optical cavities

    DEFF Research Database (Denmark)

    Kristensen, Philip Trøst; Van Vlack, C.; Hughes, S.

    2012-01-01

    We show explicitly how the commonly adopted prescription for calculating effective mode volumes is wrong and leads to uncontrolled errors. Instead, we introduce a generalized mode volume that can be easily evaluated based on the mode calculation methods typically applied in the literature, and wh......, and which allows one to compute the Purcell effect and other interesting optical phenomena in a rigorous and unambiguous way....

  16. Calculation, normalization and perturbation of quasinormal modes in coupled cavity-waveguide systems

    DEFF Research Database (Denmark)

    Kristensen, Philip Trøst; de Lasson, Jakob Rosenkrantz; Gregersen, Niels

    2014-01-01

    We show how one can use a non-local boundary condition, which is compatible with standard frequency domain methods, for numerical calculation of quasinormal modes in optical cavities coupled to waveguides. In addition, we extend the definition of the quasinormal mode norm by use of the theory of ...

  17. Normalization of quasinormal modes in leaky optical cavities and plasmonic resonators

    CERN Document Server

    Kristensen, Philip Trøst; Hughes, Stephen

    2015-01-01

    We discuss three formally different formulas for normalization of quasinormal modes currently in use for modeling optical cavities and plasmonic resonators and show that they are complementary and provide the same result. Regardless of the formula used for normalization, one can use the norm to define an effective mode volume for use in Purcell factor calculations.

  18. Transverse-mode-selectable microlens vertical-cavity surface-emitting laser

    DEFF Research Database (Denmark)

    Chung, Il-Sug; Debernardi, Pierluigi; Lee, Yong Tak

    2010-01-01

    A new vertical-cavity surface-emitting laser structure employing a thin microlens is suggested and numerically investigated. The laser can be made to emit in either a high-power Gaussian-shaped single-fundamental mode or a high-power doughnut-shaped higher-order mode. The physical origin of the m...

  19. [The influence of breathing mode on the oral cavity].

    Science.gov (United States)

    Surtel, Anna; Klepacz, Robert; Wysokińska-Miszczuk, Joanna

    2015-12-01

    Nose breathing is one of the key factors in the proper development and functioning of the oral cavity. The air passing through the nasal cavity is warmed and humidified while dust and other particulate matter is removed. It is also important as far as bone formation is concerned. The obstruction or congestions of the upper respiratory tract may negatively affect the correct and most optimal (nasal) respiratory tract. The switch from nasal to mouth breathing may lead to serious clinical consequences. Children with the clinical diagnosis of mouth breathing are usually pale, apathetic and they lack concentration and often get tired. Disorders resulting from hypoxy may also be the reason from sleep disturbances, such as frequent waking-up, nocturia, difficulties falling aslee. The main clinical manifestations of mouth breathing appear in the craniofacial structures. Mouth breathers frequently suffer from dental malocclusions and craniofacial bone abnormalities. Chronic muscle tension around the oral cavity could result in the widening of cranio-vertebral angle, posterior position of mandibula and narrow maxillary arch. Among dental alterations the most common are class II malocclusion (total or partial) with the protrusion of the anterior teeth, cross bite (unilateral or bilateral), anterior open bite and primary crowded teeth. Apart from malocclusion, chronic gingivitis, periodontitis, candida infections and halitosis are frequently present in mouth--breathing patients.

  20. Cavity quantum electrodynamics with Anderson-localized modes

    DEFF Research Database (Denmark)

    Sapienza, Luca; Nielsen, Henri Thyrrestrup; Stobbe, Søren;

    2010-01-01

    by a factor of 15 on resonance with the Anderson-localized mode, and 94% of the emitted single photons coupled to the mode. Disordered photonic media thus provide an efficient platform for quantum electrodynamics, offering an approach to inherently disorder-robust quantum information devices....

  1. Nonradiating and radiating modes excited by quantum emitters in open epsilon-near-zero cavities.

    Science.gov (United States)

    Liberal, Iñigo; Engheta, Nader

    2016-10-01

    Controlling the emission and interaction properties of quantum emitters (QEs) embedded within an optical cavity is a key technique in engineering light-matter interactions at the nanoscale, as well as in the development of quantum information processing. State-of-the-art optical cavities are based on high quality factor photonic crystals and dielectric resonators. However, wealthier responses might be attainable with cavities carved in more exotic materials. We theoretically investigate the emission and interaction properties of QEs embedded in open epsilon-near-zero (ENZ) cavities. Using analytical methods and numerical simulations, we demonstrate that open ENZ cavities present the unique property of supporting nonradiating modes independently of the geometry of the external boundary of the cavity (shape, size, topology, etc.). Moreover, the possibility of switching between radiating and nonradiating modes enables a dynamic control of the emission by, and the interaction between, QEs. These phenomena provide unprecedented degrees of freedom in controlling and trapping fields within optical cavities, as well as in the design of cavity opto- and acoustomechanical systems.

  2. Cavity quantum electrodynamics with separate photon storage and qubit readout modes.

    Science.gov (United States)

    Leek, P J; Baur, M; Fink, J M; Bianchetti, R; Steffen, L; Filipp, S; Wallraff, A

    2010-03-12

    We present the realization of a cavity quantum electrodynamics setup in which photons of strongly different lifetimes are engineered in different harmonic modes of the same cavity. We achieve this in a superconducting transmission line resonator with superconducting qubits coupled to the different modes. One cavity mode is strongly coupled to a detection line for qubit state readout, while a second long lifetime mode is used for photon storage and coherent quantum operations. We demonstrate sideband-based measurement of photon coherence, generation of n photon Fock states and the scaling of the sideband Rabi frequency with square root of n using a scheme that may be extended to realize sideband-based two-qubit logic gates.

  3. Properties of Optical Resonant Modes in Ⅲ-Nitride Semiconductor Micro-Cone Cavities

    Institute of Scientific and Technical Information of China (English)

    DAI Lun; ZHANG Bei; LIN Jing-Yu; JIANG Hong-Xing

    2001-01-01

    Arrays of Ⅲ-nitride semiconductor micro-cone cavities with a base diameter of 3.3μm were fabricated by ion beam etching. The micro-cones consisted of 58 nm thick multiple quantum wells of ln0.22Ga0.78N/In0.06Ga0.94N as well as a 1.5μm thick epilayer of GaN. Optical resonant modes from a single micro-cone could be clearly observed in the photoluminescence spectra at temperatures up to 200K under a pumping power density two orders of magnitude lower than that for the Ⅲ-nitride semiconductor micro-disk or micro-ring cavity. Using a novel optical ray tracing method, we have figured out four main types of optical resonant cavities inside the three-dimensional micro-cone, including two Fabry-Perot (F-P) mode types as well as two Whispering Gallery mode types. The three corresponding mode spacings among the four agree perfectly with the experimental results. The advantages of this new class of micro-cavity over the other micro-cavities are discussed. These findings are expected to have an impact on the design of the ultraviolet/blue micro-cavity laser diodes.

  4. Noise Effects in the Mode-Locked External Cavity Lasers

    Institute of Scientific and Technical Information of China (English)

    Nuran Dogru; M. Sadettin Ozyazici

    2003-01-01

    Effect of high level of spontaneous and carrier noise on mode-locked hybrid soliton pulse source and relative intensity noise is described. Transform limited pulses are not generated over a wide frequency range because of these noises.

  5. Advanced configuration of gravitational-wave interferometer on the base of "sensitive mode" in "white-light cavity"

    OpenAIRE

    Karapetyan, G. G.

    2002-01-01

    A novel conception of "sensitive mode" (SM) is proposed to apply in gravitational-wave advanced interferometer configuration. The SM is resonant oscillation of electromagnetic field in "white-light cavity", where the resonance line is broadened without decreasing cavity quality. The frequency of the SM is greatly susceptible to the change of cavity length, and the SM is established in a cavity with time constant smaller than a conventional mode. Due to these advantages the sensitivity and ban...

  6. Exactly solvable path integral for open cavities in terms of quasinormal modes

    CERN Document Server

    Maasen van den Brink, A

    2000-01-01

    We evaluate the finite-temperature Euclidean phase-space path integral for the generating functional of a scalar field inside a leaky cavity. Provided the source is confined to the cavity, one can first of all integrate out the fields on the outside to obtain an effective action for the cavity alone. Subsequently, one uses an expansion of the cavity field in terms of its quasinormal modes (QNMs)-the exact, exponentially damped eigenstates of the classical evolution operator, which previously have been shown to be complete for a large class of models. Dissipation causes the effective cavity action to be nondiagonal in the QNM basis. The inversion of this action matrix inherent in the Gaussian path integral to obtain the generating functional is therefore nontrivial, but can be accomplished by invoking a novel QNM sum rule. The results are consistent with those obtained previously using canonical quantization.

  7. A novel experiment for coupling a Bose-Einstein condensate with two crossed cavity modes

    Science.gov (United States)

    Leonard, Julian; Morales, Andrea; Zupancic, Philip; Donner, Tobias; Esslinger, Tilman

    2015-05-01

    Over the last decade, combining cavity quantum electrodynamics and quantum gases made it possible to explore the coupling of quantized light fields to coherent matter waves, leading e.g. to new optomechanical phenomena and the realization of quantum phase transitions. Triggered by the interest to study setups with more complex cavity geometries, we built a novel, highly flexible experimental system for coupling a Bose-Einstein condensate (BEC) with optical cavities, which allows to switch the cavity setups by means of an interchangeable science platform. report on our latest results on coupling a Bose-Einstein condensate with two crossed cavity modes intersecting under an angle of 60°. The mirrors have been machined in a way to spatially approach them, thus obtaining maximum single atom coupling rates of several MHz. This setup will allow the study of self-ordered phases in different lattice shapes, such as hexagonal and triangular geometries.

  8. Enhanced Sensitivity in a Superluminal Single Mode DPAL Cavity at Room Temperature

    Science.gov (United States)

    Abi-Salloum, Tony; Yablon, Joshua; Tseng, Shih; Shahriar, Selim

    2012-06-01

    The note beat between two counter-propagating beams in a cavity is used to measure the effective change of the length of the cavity or interferometer for applications such as optical gyroscopes, vibrometers, and gravitational wave detectors. We show in this talk how a superluminal single mode laser cavity can enhance the measured note beat dramatically. We consider the inhomogeneous broadening case and study the dependence of the enhancement factor on few key parameters. We also show how Diode Pump Alkali Lasers (DPAL) are excellent candidates for such devices. Using a Rubidium based DPAL, we study the characteristics of these lasers and their effect on the proposed enhanced sensitivity.

  9. Comparison of high order modes damping techniques for 800 MHz single cell superconducting cavities

    CERN Document Server

    Shashkov, Ya V; Zobov, M M

    2014-01-01

    Currently, applications of 800 MHz harmonic cavities in both bunch lengthening and shortening regimes are under consideration and discussion in the framework of the High Luminosity LHC project. In this paper we study electromagnetic characteristics of high order modes (HOM) for a single cell 800 MHz superconducting cavity and arrays of such cavities connected by drifts tubes. Different techniques for the HOM damping such as beam pipe grooves, coaxial-notch loads, fluted beam pipes etc. are investigated and compared. The influence of the sizes and geometry of the drift tubes on the HOM damping is analyzed.

  10. Dispersionless gaps and cavity modes in photonic crystals containing hyperbolic metamaterials

    Science.gov (United States)

    Xue, Chun-hua; Ding, Yaqiong; Jiang, Hai-tao; Li, Yunhui; Wang, Zhan-shan; Zhang, Ye-wen; Chen, Hong

    2016-03-01

    We theoretically study dispersionless gaps and cavity modes in one-dimensional photonic crystals composed of hyperbolic metamaterials and dielectric. Bragg gaps in conventional all-dielectric photonic crystals are always dispersive because propagating phases in two kinds of dielectrics decrease with incident angle. Here, based on phase variation compensation between a hyperbolic metamaterial layer and an isotropic dielectric layer, the dispersion of the gap can be offset and thus a dispersionless gap can be realized. Moreover, the dispersionless property of such gap has a wide parameter space. The dispersionless gap can be used to realize a dispersionless cavity mode. The dispersionless gaps and cavity modes will possess significant applications for all-angle reflectors, high-Q filters excited with finite-sized sources, and nonlinear wave mixing processes.

  11. Waves and rays in plano-concave laser cavities: I. Geometric modes in the paraxial approximation

    Science.gov (United States)

    Barré, N.; Romanelli, M.; Lebental, M.; Brunel, M.

    2017-05-01

    Eigenmodes of laser cavities are studied theoretically and experimentally in two companion papers, with the aim of making connections between undulatory and geometric properties of light. In this first paper, we focus on macroscopic open-cavity lasers with localized gain. The model is based on the wave equation in the paraxial approximation; experiments are conducted with a simple diode-pumped Nd:YAG laser with a variable cavity length. After recalling fundamentals of laser beam optics, we consider plano-concave cavities with on-axis or off-axis pumping, with emphasis put on degenerate cavity lengths, where modes of different order resonate at the same frequency, and combine to form surprising transverse beam profiles. Degeneracy leads to the oscillation of so-called geometric modes whose properties can be understood, to a certain extent, also within a ray optics picture. We first provide a heuristic description of these modes, based on geometric reasoning, and then show more rigorously how to derive them analytically by building wave superpositions, within the framework of paraxial wave optics. The numerical methods, based on the Fox-Li approach, are described in detail. The experimental setup, including the imaging system, is also detailed and relatively simple to reproduce. The aim is to facilitate implementation of both the numerics and of the experiments, and to show that one can have access not only to the common higher-order modes but also to more exotic patterns.

  12. Intra-cavity generation of high order LGpl modes

    CSIR Research Space (South Africa)

    Ngcobo, S

    2012-08-01

    Full Text Available This work deals with the generation of symmetrical high order Laguerre Gaussian modes. These high order Laguerre-Gaussian beams are generated by forcing the laser using an annular binary Diffractive Optical Element whose geometry is in connection...

  13. New developed cylindrical TM010 mode EPR cavity for X-band in vivo tooth dosimetry.

    Directory of Open Access Journals (Sweden)

    Guo Junwang

    Full Text Available EPR tooth in vivo dosimetry is an attractive approach for initial triage after unexpected nuclear events. An X-band cylindrical TM010 mode resonant cavity was developed for in vivo tooth dosimetry and used in EPR applications for the first time. The cavity had a trapezoidal measuring aperture at the exact position of the cavity's cylindrical wall where strong microwave magnetic field H1 concentrated and weak microwave electric field E1 distributed. Theoretical calculations and simulations were used to design and optimize the cavity parameters. The cavity features were evaluated by measuring DPPH sample, intact incisor samples embed in a gum model and the rhesus monkey teeth. The results showed that the cavity worked at designed frequency and had the ability to make EPR spectroscopy in relative high sensitivity. Sufficient modulation amplitude and microwave power could be applied into the aperture. Radiation induced EPR signal could be observed remarkably from 1 Gy irradiated intact incisor within only 30 seconds, which was among the best in scan time and detection limit. The in vivo spectroscopy was also realized by acquiring the radiation induced EPR signal from teeth of rhesus monkey whose teeth was irradiated by dose of 2 Gy. The results suggested that the cavity was sensitive to meet the demand to assess doses of significant level in short time. This cavity provided a very potential option for the development of X-band in vivo dosimetry.

  14. Polariton Analysis of a Four-Level Atom Strongly Coupled to a Cavity Mode

    CERN Document Server

    Rebic, S; Tan, S M

    2002-01-01

    We present a complete analytical solution for a single four-level atom strongly coupled to a cavity field mode and driven by external coherent laser fields. The four-level atomic system consists of a three-level subsystem in an EIT configuration, plus an additional atomic level; this system has been predicted to exhibit a photon blockade effect. The solution is presented in terms of polaritons. An effective Hamiltonian obtained by this procedure is analyzed from the viewpoint of an effective two-level system, and the dynamic Stark splitting of dressed states is discussed. The fluorescence spectrum of light exiting the cavity mode is analyzed and relevant transitions identified.

  15. Tunable mode-locked laser with micro-air gap cavity

    Science.gov (United States)

    Ahmad, H.; Aidit, S. N.; Hassan, N. A.; Ooi, S. I.; Tiu, Z. C.

    2017-02-01

    A tunable mode-locked laser with a micro-air gap cavity acting as a high resolution tuning is proposed and demonstrated. The laser utilizes the nonlinear polarization technique in the cavity to obtain a reliable and stable mode locking over the whole tuning range at a resolution of 1 nm. The micro-air gap is constructed by aligning two fiber facets coaxially, and the variation of micro-air gap introduces a tuning mechanism where it changes the gain saturation compensation in the gain medium and thus induces wavelength shifting on the generated solitons.

  16. Large ion Coulomb crystals: A near-ideal medium for coupling optical cavity modes to matter

    DEFF Research Database (Denmark)

    Dantan, Aurélien; Albert, Magnus; Marler, Joan

    2009-01-01

    We present an investigation of the coherent coupling of various transverse field modes of an optical cavity to ion Coulomb crystals. The obtained experimental results, which include the demonstration of identical collective coupling rates for different transverse modes of a cavity field to ions...... in the same large Coulomb crystal, are in excellent agreement with theoretical predictions. The results furthermore suggest that Coulomb crystals in the future may serve as near-ideal media for high-fidelity multimode quantum information processing and communication purposes, including the generation...

  17. Use of proper cavity loss for a stable single-longitudinal-mode erbium fiber laser

    Science.gov (United States)

    Yeh, Chien-Hung; Zhuang, Yuan-Hong; Tsai, Ning; Chow, Chi-Wai; Chen, Jing-Heng

    2017-06-01

    A stable and selectable erbium-doped fiber (EDF) ring laser configuration with single-longitudinal-mode (SLM) output is proposed and demonstrated in this paper. In the proposed laser scheme, a proper cavity loss is utilized for significant suppression of the side mode. In the experiment, the different coupling ratios required to produce various cavity losses in the proposed fiber laser are analyzed. Here, to reach the wavelength selection, several fiber Bragg gratings (FBGs) and an optical tunable bandpass filter (OTBF) in the C-band range are employed for demonstration. In addition, the output performance with respect to stability and SLM in the proposed EDF ring laser are also investigated simultaneously.

  18. Pulse shaping in mode-locked fiber lasers by in-cavity spectral filter.

    Science.gov (United States)

    Boscolo, Sonia; Finot, Christophe; Karakuzu, Huseyin; Petropoulos, Periklis

    2014-02-01

    We numerically show the possibility of pulse shaping in a passively mode-locked fiber laser by inclusion of a spectral filter into the laser cavity. Depending on the amplitude transfer function of the filter, we are able to achieve various regimes of advanced temporal waveform generation, including ones featuring bright and dark parabolic-, flat-top-, triangular- and saw-tooth-profiled pulses. The results demonstrate the strong potential of an in-cavity spectral pulse shaper for controlling the dynamics of mode-locked fiber lasers.

  19. Dynamic mode decomposition of turbulent cavity flows for self-sustained oscillations

    Energy Technology Data Exchange (ETDEWEB)

    Seena, Abu [Department of Mechanical Engineering, KAIST, 291 Daehak-ro, Yuseong-gu, Daejeon 305-701 (Korea, Republic of); Sung, Hyung Jin, E-mail: hjsung@kaist.ac.kr [Department of Mechanical Engineering, KAIST, 291 Daehak-ro, Yuseong-gu, Daejeon 305-701 (Korea, Republic of)

    2011-12-15

    Highlights: Black-Right-Pointing-Pointer DMD modes were extracted from two cavity flow data set at Re{sub D} = 12,000 and 3000. Black-Right-Pointing-Pointer At Re{sub D} = 3000, frequencies of boundary layer and shear layer structures coincides. Black-Right-Pointing-Pointer Boundary layer structures exceed in size with shear layer structures. Black-Right-Pointing-Pointer At Re{sub D} = 12,000, structure showed coherence leading to self-sustained oscillations. Black-Right-Pointing-Pointer Hydrodynamic resonance occurs if coherence exists in wavenumber and frequency. - Abstract: Self-sustained oscillations in a cavity arise due to the unsteady separation of boundary layers at the leading edge. The dynamic mode decomposition method was employed to analyze the self-sustained oscillations. Two cavity flow data sets, with or without self-sustained oscillations and possessing thin or thick incoming boundary layers (Re{sub D} = 12,000 and 3000), were analyzed. The ratios between the cavity depth and the momentum thickness (D/{theta}) were 40 and 4.5, respectively, and the cavity aspect ratio was L/D = 2. The dynamic modes extracted from the thick boundary layer indicated that the upcoming boundary layer structures and the shear layer structures along the cavity lip line coexisted with coincident frequency space but with different wavenumber space, whereas structures with a thin boundary layer showed complete coherence among the modes to produce self-sustained oscillations. This result suggests that the hydrodynamic resonances that gave rise to the self-sustained oscillations occurred if the upcoming boundary layer structures and the shear layer structures coincided, not only in frequencies, but also in wavenumbers. The influences of the cavity dimensions and incoming momentum thickness on the self-sustained oscillations were examined.

  20. Observational evidence of cavity modes in the earth's magnetosphere

    Energy Technology Data Exchange (ETDEWEB)

    Crowley, G. (National Center for Atmospheric Research, Boulder, CO (United States)); Hughes, W.J. (Boston Univ., MA (United States)); Jones, T.B. (Univ. of Leicester (England))

    1987-11-01

    On November 30, 1982, two large-amplitude Pc 5 pulsations were observed at Tromso, Norway, by both the European Incoherent Scatter (EISCAT) radar and ground-based magnetometers. The pulsations were excited by a sudden impulse. Their amplitude subsequently decreased, allowing a damping rate to be determined. Estimates of the height-integrated Pedersen conductivity obtained from the EISCAT data permit theoretical pulsation damping rates to be predicted. However, the theoretical damping rates are much greater than those actually measured, which indicates that energy was continuously fed into the field line resonance after its onset. The most likely source of this energy is coupling from a hydromagnetic cavity mode. If this is the case, the measured pulsation damping rate is controlled by the damping of the cavity mode rather than energy dissipation from the field lines resonance. An upper limit of {gamma}/{omega} = 0.08 is obtained from the coupling efficiency between the two modes. The energy dissipated in the ionosphere by these pulsations was {approximately}4 {times} 10{sup 12} J. To store this energy in the cavity mode requires an initial cavity mode amplitude of only {approximately}0.4 nT. Long-period magnetic perturbations of this amplitude would be difficult to detect in existing spaceborne magnetometer data sets.

  1. Flow field characteristics analysis and combustion modes classification for a strut/cavity dual-mode combustor

    Science.gov (United States)

    Zhang, Chenlin; Chang, Juntao; Zhang, Yuanshi; Wang, Youyin; Bao, Wen

    2017-08-01

    Experimental and numerical study of a strut/cavity dual-mode combustor has been conducted in this paper. Under different fuel equivalence ratio and allocation proportion conditions, the pressure distribution and flow field structure of combustor show distinct characteristics. For strut fuel injecting at a low equivalence ratio, the luminosity images show that combustion zone distributes in the shear layer behind the strut. The wall fuel injecting before strut would change the starting point of pressure rising. Based on the flow field structure, the dual-mode combustor operation process is classified into three combustion modes, including scramjet mode, weak ramjet mode and strong ramjet mode. Because of a strong interaction of the shock wave with the boundary layer, weak ramjet mode has a stronger isolator compression effect and higher combustion efficiency than scramjet mode. With heat release increasing, the thermal throat formation is an indication of the strong ramjet mode, which has a subsonic gap in the isolator. Further, by judging the pressure from dominant pressure sensor before the strut, the three different combustion modes could be classified. Comparing the specific impulse of combustor, it has an obvious distinction in the different combustion modes.

  2. Tunable single and dual mode operation of an external cavity quantum-dot injection laser

    Energy Technology Data Exchange (ETDEWEB)

    Biebersdorf, A [Photonics and Optoelectronics Group, Physics Department and CeNS, Ludwig-Maximilians-Universitaet, Amalienstrasse 54, D-80799 Munich (Germany); Lingk, C [Photonics and Optoelectronics Group, Physics Department and CeNS, Ludwig-Maximilians-Universitaet, Amalienstrasse 54, D-80799 Munich (Germany); De Giorgi, M [Photonics and Optoelectronics Group, Physics Department and CeNS, Ludwig-Maximilians-Universitaet, Amalienstrasse 54, D-80799 Munich (Germany); Feldmann, J [Photonics and Optoelectronics Group, Physics Department and CeNS, Ludwig-Maximilians-Universitaet, Amalienstrasse 54, D-80799 Munich (Germany); Sacher, J [Sacher Lasertechnik GmbH, Hannah Arendt Strasse 3-7, D-35037 Marburg (Germany); Arzberger, M [Walter Schottky Institut, Technische Universitaet Muenchen, Am Coulombwall, D-85748 Garching (Germany); Ulbrich, C [Walter Schottky Institut, Technische Universitaet Muenchen, Am Coulombwall, D-85748 Garching (Germany); Boehm, G [Walter Schottky Institut, Technische Universitaet Muenchen, Am Coulombwall, D-85748 Garching (Germany); Amann, M-C [Walter Schottky Institut, Technische Universitaet Muenchen, Am Coulombwall, D-85748 Garching (Germany); Abstreiter, G [Walter Schottky Institut, Technische Universitaet Muenchen, Am Coulombwall, D-85748 Garching (Germany)

    2003-08-21

    We investigate quantum-dot (QD) lasers in an external cavity using Littrow and Littman configurations. Here, we report on a continuously tunable QD laser with a broad tuning range from 1047 to 1130 nm with high stability and efficient side mode suppression. The full-width at half-maximum of the laser line is 0.85 nm determined mainly by the quality of the external grating. This laser can be operated in a dual-mode modus, where the mode-spacing can be tuned continuously between 1.1 and 34 nm. Simultaneous emission of the two laser modes is shown by sum frequency generation experiments.

  3. Comparing the Quasi-Normal and Natural Modes of an open cavity

    CERN Document Server

    Settimi, A; Hoenders, B J; Hauss, J W; Napoli, A; Messina, A; Perina, J; Sibilia, C; Bertolotti, M

    2009-01-01

    The present paper proposes, for the first time to the best of our knowledge, a systematic comparison between the Quasi Normal Modes (QNMs) and the Natural Modes (NMs) for one-dimensional (1D) two side opened cavities. We clarify, in classical electrodynamics, why, for the description of an e.m. field outgoing from a one-layer homogeneous structure (as a laser cavity), the QNM eigen-functions should be the most suitable expansion basis, whilst, for discussing the scattering properties of a multi-layer inhomogeneous structure (as a Photonic Crystal (PC)), the NM eigen-functions seem a better choice. The QNM eigen-frequencies and eigen-functions are calculated for a linear Fabry-Perot (FP) cavity. The first-order Born approximation is applied to the same cavity in order to make a comparison between the first-order Born approximated and the actual QNM eigen-functions of the cavity. We prove that the first-order Born approximation for a FP cavity introduces a symmetry breaking: in fact, each Born approximated QNM ...

  4. Exploring the distinction between experimental resonant modes and theoretical eigenmodes: From vibrating plates to laser cavities

    Science.gov (United States)

    Tuan, P. H.; Wen, C. P.; Yu, Y. T.; Liang, H. C.; Huang, K. F.; Chen, Y. F.

    2014-02-01

    Experimentally resonant modes are commonly presumed to correspond to eigenmodes in the same bounded domain. However, the one-to-one correspondence between theoretical eigenmodes and experimental observations is never reached. Theoretically, eigenmodes in numerous classical and quantum systems are the solutions of the homogeneous Helmholtz equation, whereas resonant modes should be solved from the inhomogeneous Helmholtz equation. In the present paper we employ the eigenmode expansion method to derive the wave functions for manifesting the distinction between eigenmodes and resonant modes. The derived wave functions are successfully used to reconstruct a variety of experimental results including Chladni figures generated from the vibrating plate, resonant patterns excited from microwave cavities, and lasing modes emitted from the vertical cavity.

  5. Beam position diagnostics with higher order modes in third harmonic superconducting accelerating cavities

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Pei

    2013-02-15

    Higher order modes (HOM) are electromagnetic resonant fields. They can be excited by an electron beam entering an accelerating cavity, and constitute a component of the wakefield. This wakefield has the potential to dilute the beam quality and, in the worst case, result in a beam-break-up instability. It is therefore important to ensure that these fields are well suppressed by extracting energy through special couplers. In addition, the effect of the transverse wakefield can be reduced by aligning the beam on the cavity axis. This is due to their strength depending on the transverse offset of the excitation beam. For suitably small offsets the dominant components of the transverse wakefield are dipole modes, with a linear dependence on the transverse offset of the excitation bunch. This fact enables the transverse beam position inside the cavity to be determined by measuring the dipole modes extracted from the couplers, similar to a cavity beam position monitor (BPM), but requires no additional vacuum instrumentation. At the FLASH facility in DESY, 1.3 GHz (known as TESLA) and 3.9 GHz (third harmonic) cavities are installed. Wakefields in 3.9 GHz cavities are significantly larger than in the 1.3 GHz cavities. It is therefore important to mitigate the adverse effects of HOMs to the beam by aligning the beam on the electric axis of the cavities. This alignment requires an accurate beam position diagnostics inside the 3.9 GHz cavities. It is this aspect that is focused on in this thesis. Although the principle of beam diagnostics with HOM has been demonstrated on 1.3 GHz cavities, the realization in 3.9 GHz cavities is considerably more challenging. This is due to the dense HOM spectrum and the relatively strong coupling of most HOMs amongst the four cavities in the third harmonic cryo-module. A comprehensive series of simulations and HOM spectra measurements have been performed in order to study the modal band structure of the 3.9 GHz cavities. The dependencies of

  6. Entanglement of resonantly coupled field modes in cavities with vibrating boundaries

    CERN Document Server

    Andreata, M A; Dodonov, V V

    2002-01-01

    We study time dependence of various measures of entanglement (covariance entanglement coefficient, purity entanglement coefficient, normalized distance coefficient, entropic coefficients) between resonantly coupled modes of the electromagnetic field in ideal cavities with oscillating boundaries. Two types of cavities are considered: a three-dimensional cavity possessing eigenfrequencies $\\omega_3=3\\omega_1$, whose wall oscillates at the frequency $\\omega_w=2\\omega_1$, and a one-dimensional (Fabry--Perot) cavity with an equidistant spectrum $\\omega_n= n\\omega_1$, when the distance between perfect mirrors oscillates at the frequencies $\\omega_1$ and $2\\omega_1$. The behaviour of entanglement measures in these cases turns out to be completely different, although all three coefficients demonstrate qualitatively similar time dependences in each case (except for some specific situations, where the covariance entanglement coefficient, based on traces of covariance submatrices, seems to be essentially more sensitive ...

  7. Measurement of electrodynamics characteristics of higher order modes for harmonic cavity at 2400 MHz

    Science.gov (United States)

    Shashkov, Ya V.; Sobenin, N. P.; Gusarova, M. A.; Lalayan, M. V.; Bazyl, D. S.; Donetskiy, R. V.; Orlov, A. I.; Zobov, M. M.; Zavadtsev, A. A.

    2016-09-01

    In the frameworks of the High Luminosity Large Hadron Collider (HL-LHC) upgrade program an application of additional superconducting harmonic cavities operating at 800 MHz is currently under discussion. As a possible candidate, an assembly of two cavities with grooved beam pipes connected by a drift tube and housed in a common cryomodule, was proposed. In this article we discuss measurements of loaded Q-factors of higher order modes (HOM) performed on a scaled aluminium single cell cavity prototype with the fundamental frequency of 2400 MHz and on an array of two such cavities connected by a narrow beam pipe. The measurements were performed for the system with and without the matching load in the drift tube..

  8. Test Results of the 3.9 GHz Cavity at Fermilab

    CERN Document Server

    Solyak, N

    2004-01-01

    Fermilab is developing two types of 3.9 GHz superconducting cavities to improve performances of A0 and TTF photoinjectors. In frame of this project we have built and tested two nine-cell copper models and one 3-cell niobium accelertating cavity and series of deflecting cavities. Properties of the high order modes were carefully studied in a chain of two copper cavities at room temperature. High gradient performance were tested at helium temperature. Achieved gradients and surface resistances are exceed goal parameters. In paper we discuss results of cold tests of the 3-cell accelerating and deflecting cavities.

  9. Double Quarter Wave Crab Cavity Field Profile Analysis and Higher Order Mode Characterization

    Energy Technology Data Exchange (ETDEWEB)

    Marques, Carlos [Brookhaven National Lab. (BNL), Upton, NY (United States). Accelerator R and D Div.; Stony Brook Univ., NY (United States). Physics and Astronomy Dept.; Xiao, B. P. [Brookhaven National Lab. (BNL), Upton, NY (United States). Accelerator R and D Div.; Belomestnykh, S. [Brookhaven National Lab. (BNL), Upton, NY (United States). Accelerator R and D Div.; Stony Brook Univ., NY (United States). Physics and Astronomy Dept.

    2014-06-01

    The Large Hadron Collider (LHC) is underway for a major upgrade to increase its luminosity by an order of magnitude beyond its original design specifications. This novel machine configuration known as the High Luminosity LHC (HL-LHC) will rely on various innovative technologies including very compact and ultra-precise superconducting crab cavities for beam rotation. A double quarter wave crab cavity (DQWCC) has been designed at Brookhaven National Laboratory for the HL-LHC. This cavity as well as the structural support components were fabricated and assembled at Niowave. The field profile of the crabbing mode for the DQWCC was investigated using a phase shift bead pulling technique and compared with simulated results to ensure proper operation or discover discrepancies from modeled results and/or variation in fabrication tolerances. Higher-Order Mode (HOM) characterization was also performed and correlated with simulations.

  10. Tunable mode-locked semiconductor laser with Bragg mirror external cavity

    DEFF Research Database (Denmark)

    Yvind, Kresten; Jørgensen, T.; Birkedal, Dan

    2002-01-01

    We present a simplified design for a wavelength tunable external cavity mode-locked laser by employing a wedged GaAs/AlGaAs Bragg mirror. The device emits 4-6 ps pulses at 10 GHz and is tunable over 15 nm. Although, in the present configuration, tunability is limited to 15 nm, however, we have...

  11. Performance of external cavity mode-locked semiconductor lasers employing reverse biased saturable absorbers

    DEFF Research Database (Denmark)

    Yvind, Kresten; Skovgaard, P.M.W.; Mørk, Jesper;

    2002-01-01

    We have experimentally investigated the performance of external cavity mode-locked semiconductor lasers employing reverse biased saturable absorbers. We have measured the magnitude of trailing pulses when varying the chip length and studied the pulse quality when changing the driving conditions...

  12. Single mode cavities for parametric oscillatory instability suppression in laser gravitational wave detectors

    Science.gov (United States)

    Poplavskiy, Mikhail V.

    Parametric oscillatory instability will be a serious problem restricting the power circulating in laser gravitation wave detectors (aLIGO). For parametric oscillatory instability suppression we suggest to use practically "single mode" Fabry-Perot (FP) cavity with little changed mirror's specular surface.

  13. Proton acceleration by RF TE{sub 11} mode in a cylindrical cavity

    Energy Technology Data Exchange (ETDEWEB)

    Sobajima, Masaaki; Yoshikawa, Kiyoshi; Ohnishi, Masami; Yamamoto, Yasushi; Masuda, Kai [Kyoto Univ., Uji (Japan). Inst. of Advanced Energy

    1997-03-01

    We found that protons are accelerated significantly by RF TE{sub 11} mode in a cylindrical cavity. In this method, protons get the perpendicular kinetic energy, so we thought it might be a compact accelerator, and studied the feasibility by numerical simulation. (author)

  14. Cavity modes with optical orbital angular momentum in a metamaterial ring based on transformation optics.

    Science.gov (United States)

    Wu, H W; Wang, F; Dong, Y Q; Shu, F Z; Zhang, K; Peng, R W; Xiong, X; Wang, Mu

    2015-12-14

    In this work, we theoretically study the cavity modes with transverse orbital angular momentum in metamaterial ring based on transformation optics. The metamaterial ring is designed to transform the straight trajectory of light into the circulating one by enlarging the azimuthal angle, effectively presenting the modes with transverse orbital angular momentum. The simulation results confirm the theoretical predictions, which state that the transverse orbital angular momentum of the mode not only depends on the frequency of the incident light, but also depends on the transformation scale of the azimuthal angle. Because energy dissipation inevitably reduces the field amplitude of the modes, the confined electromagnetic energy and the quality factor of the modes inside the ring are also studied in order to evaluate the stability of those cavity modes. The results show that the metamaterial ring can effectively confine light with a high quality factor and maintain steady modes with the orbital angular momentum, even if the dimension of the ring is much smaller than the wavelength of the incident light. This technique for exploiting the modes with optical transverse orbital angular momentum may provides a unique platform for applications related to micromanipulation.

  15. Investigations of repetition rate stability of a mode-locked quantum dot semiconductor laser in an auxiliary optical fiber cavity

    DEFF Research Database (Denmark)

    Breuer, Stefan; Elsässer, Wolfgang; McInerney, J.G.

    2010-01-01

    We have investigated experimentally the pulse train (mode beating) stability of a monolithic mode-locked multi-section quantum-dot laser with an added passive auxiliary optical fiber cavity. Addition of the weakly coupled (¿ -24dB) cavity reduces the current-induced shift d¿/dI of the principal...

  16. Existence of Majorana fermion mode and Dirac equation in cavity quantum electrodynamics

    Energy Technology Data Exchange (ETDEWEB)

    Sarkar, Sujit, E-mail: sujit.tifr@gmail.com

    2015-10-15

    We present the results of low lying collective mode of coupled optical cavity arrays. We derive the Dirac equation for this system and explain the existence of Majorana fermion mode in the system. We present quite a few analytical relations between the Rabi frequency oscillation and the atom–photon coupling strength to explain the different physical situation of our study and also the condition for massless collective mode in the system. We present several analytical relations between the Dirac spinor field, order and disorder operators for our systems. We also show that the Luttinger liquid physics is one of the intrinsic concepts in our system.

  17. Comparative Simulation Studies of Multipacting in Higher-Order-Mode Couplers of Superconducting RF Cavities

    Energy Technology Data Exchange (ETDEWEB)

    Li, Y. M. [Peking University, Beijing (China); Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Liu, Kexin [Peking University, Beijing (China); Geng, Rongli [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States)

    2014-02-01

    Multipacting (MP) in higher-order-mode (HOM) couplers of the International Linear Collider (ILC) baseline cavity and the Continuous Electron Beam Accelerator Facility (CEBAF) 12 GeV upgrade cavity is studied by using the ACE3P suites, developed by the Advanced Computations Department at SLAC. For the ILC cavity HOM coupler, the simulation results show that resonant trajectories exist in three zones, corresponding to an accelerating gradient range of 0.6-1.6 MV/m, 21-34 MV/m, 32-35 MV/m, and > 40MV/m, respectively. For the CEBAF 12 GeV upgrade cavity HOM coupler, resonant trajectories exist in one zone, corresponding to an accelerating gradient range of 6-13 MV/m. Potential implications of these MP barriers are discussed in the context of future high energy pulsed as well as medium energy continuous wave (CW) accelerators based on superconducting radio frequency cavities. Frequency scaling of MP's predicted in HOM couplers of the ILC, CBEAF upgrade, SNS and FLASH third harmonic cavity is given and found to be in good agreement with the analytical result based on the parallel plate model.

  18. Beam position diagnostics with higher order modes in third harmonic superconducting accelerating cavities

    CERN Document Server

    Zhang, P; Baboi, Nicoleta

    2012-01-01

    Higher order modes (HOM) are electromagnetic resonant fields. They can be excited by an electron beam entering an accelerating cavity, and constitute a component of the wakefield. This wakefield has the potential to dilute the beam quality and, in the worst case, result in a beam-break-up instability. It is therefore important to ensure that these fields are well suppressed by extracting energy through special couplers. In addition, the effect of the transverse wakefield can be reduced by aligning the beam on the cavity axis. This is due to their strength depending on the transverse offset of the excitation beam. For suitably small offsets the dominant components of the transverse wakefield are dipole modes, with a linear dependence on the transverse offset of the excitation bunch. This fact enables the transverse beam position inside the cavity to be determined by measuring the dipole modes extracted from the couplers, similar to a cavity beam position monitor (BPM), but requires no additional vacuum instrum...

  19. Near-field coupling and resonant cavity modes in plasmonic nanorod metamaterials.

    Science.gov (United States)

    Song, Haojie; Zhang, Junxi; Fei, Guangtao; Wang, Junfeng; Jiang, Kang; Wang, Pei; Lu, Yonghua; Iorsh, Ivan; Xu, Wei; Jia, Junhui; Zhang, Lide; Kivshar, Yuri S; Zhang, Lin

    2016-10-14

    Plasmonic resonant cavities are capable of confining light at the nanoscale, resulting in both enhanced local electromagnetic fields and lower mode volumes. However, conventional plasmonic resonant cavities possess large Ohmic losses at metal-dielectric interfaces. Plasmonic near-field coupling plays a key role in a design of photonic components based on the resonant cavities because of the possibility to reduce losses. Here, we study the plasmonic near-field coupling in the silver nanorod metamaterials treated as resonant nanostructured optical cavities. Reflectance measurements reveal the existence of multiple resonance modes of the nanorod metamaterials, which is consistent with our theoretical analysis. Furthermore, our numerical simulations show that the electric field at the longitudinal resonances forms standing waves in the nanocavities due to the near-field coupling between the adjacent nanorods, and a new hybrid mode emerges due to a coupling between nanorods and a gold-film substrate. We demonstrate that this coupling can be controlled by changing the gap between the silver nanorod array and gold substrate.

  20. Near-field coupling and resonant cavity modes in plasmonic nanorod metamaterials

    Science.gov (United States)

    Song, Haojie; Zhang, Junxi; Fei, Guangtao; Wang, Junfeng; Jiang, Kang; Wang, Pei; Lu, Yonghua; Iorsh, Ivan; Xu, Wei; Jia, Junhui; Zhang, Lide; Kivshar, Yuri S.; Zhang, Lin

    2016-10-01

    Plasmonic resonant cavities are capable of confining light at the nanoscale, resulting in both enhanced local electromagnetic fields and lower mode volumes. However, conventional plasmonic resonant cavities possess large Ohmic losses at metal-dielectric interfaces. Plasmonic near-field coupling plays a key role in a design of photonic components based on the resonant cavities because of the possibility to reduce losses. Here, we study the plasmonic near-field coupling in the silver nanorod metamaterials treated as resonant nanostructured optical cavities. Reflectance measurements reveal the existence of multiple resonance modes of the nanorod metamaterials, which is consistent with our theoretical analysis. Furthermore, our numerical simulations show that the electric field at the longitudinal resonances forms standing waves in the nanocavities due to the near-field coupling between the adjacent nanorods, and a new hybrid mode emerges due to a coupling between nanorods and a gold-film substrate. We demonstrate that this coupling can be controlled by changing the gap between the silver nanorod array and gold substrate.

  1. Dynamic Behavior of Lambda-Type Three-Level Atoms and Two-Mode Cavity Field

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    A system comprising of Lambda-type three-level atoms and the two-mode cavity field is considered in this paper. Under the adiabatical approximation and the large detuning condition, the effective Hamiltonian of the system in the interaction picture can be given out. If the two identical three-level atoms pass through the cavity in turn, the entangled state atoms can be generated. When the interaction time is taken to an appropriate value, the maximally entangled states are created. At the same time, the dynamic behaviors of the system are studied in detail.

  2. Cavities

    Science.gov (United States)

    ... may pass these bacteria to a child through kissing, sampling the child's food, or sharing eating utensils. ... pass decay-causing bacteria to their children through kissing or sharing eating utensils. Symptoms of Cavities Whether ...

  3. Long-term frequency stabilization system for external cavity diode laser based on mode boundary detection.

    Science.gov (United States)

    Xu, Zhouxiang; Huang, Kaikai; Jiang, Yunfeng; Lu, Xuanhui

    2011-12-01

    We have realized a long-term frequency stabilization system for external cavity diode laser (ECDL) based on mode boundary detection method. In this system, the saturated absorption spectroscopy was used. The current and the grating of the ECDL were controlled by a computer-based feedback control system. By checking if there are mode boundaries in the spectrum, the control system determined how to adjust current to avoid mode hopping. This procedure was executed periodically to ensure the long-term stabilization of ECDL in the absence of mode hops. This diode laser system with non-antireflection coating had operated in the condition of long-term mode-hop-free stabilization for almost 400 h, which is a significant improvement of ECDL frequency stabilization system.

  4. Active mode locking of quantum cascade lasers operating in external ring cavity

    CERN Document Server

    Revin, D G; Wang, Y; Cockburn, J W; Belyanin, A

    2015-01-01

    Stable ultrashort light pulses and frequency combs generated by mode-locked lasers have many important applications including high-resolution spectroscopy, fast chemical detection and identification, studies of ultrafast processes, and laser metrology. While compact mode-locked lasers emitting in the visible and near infrared range have revolutionized photonic technologies, the systems operating in the mid-infrared range where most gases have their strong absorption lines, are bulky and expensive and rely on nonlinear frequency down-conversion. Quantum cascade lasers are the most powerful and versatile compact light sources in the mid-infrared range, yet achieving their mode locked operation remains a challenge despite dedicated effort. Here we report the first demonstration of active mode locking of an external-cavity quantum cascade laser. The laser operates in the mode-locked regime at room temperature and over the full dynamic range of injection currents of a standard commercial laser chip.

  5. Tunable cavity-enhanced photon pairs source in Hermite-Gaussian mode

    CERN Document Server

    Zhou, Zhi-Yuan; Ding, Dong-Sheng; Zhang, Wei; Shi, Shuai; Shi, Bao-Sen; Guo, Guang-Can

    2015-01-01

    The spatial modes of light have grasped great research interests because of its great potentials in optical communications, optical manipulation and trapping, optical metrology and quantum information processing. Here we report on generating of photon pairs in Hermite-Gaussian (HG) mode in a type-I optical parametric oscillator (OPO) operated far below threshold. The bandwidths of the photon pairs are 11.4 MHz and 20.8MHz for two different HG modes respectively, which is capable to be stored in cold Rubidium atomic ensembles. From correlation measurements, non-classical properties of HG modes in different directions are verified by tuning the cavity. Our study provides an effective way to generate photon pairs with narrow bandwidth in high order spatial modes for high dimensional quantum communication.

  6. Few-mode vertical-cavity surface-emitting lasers for space-division multiplexing

    Science.gov (United States)

    Su, Yaman; Yu, Lijuan; Guo, Xia; Zhang, Xing; Liu, Jianguo; Zhu, Ninghua

    2017-09-01

    In order to choose the proper radius of oxide aperture for few-mode vertical-cavity surface-emitting lasers (VCSELs), the influences of oxide aperture size on the multi-transverse-mode behaviors are investigated in detail. By establishing the effective refractive index model to simulate VCSELs with different radii of oxide apertures, the wavelength and corresponding order of different modes are obtained. VCSELs with three kinds of oxide apertures are manufactured. Then the multi-transverse-mode spectra and near-field are measured. It is found that when the radius is between 1.5 and 4.5 {{μ }}{{m}}, few-mode VCSELs can be implemented. The 2.5 {{μ }}{{m}} VCSEL manufactured in this paper only emits LP01 mode and LP21 mode. Since the space distance between the two modes is 2 {{μ }}{{m}}, it is expected to realize direct-modulation few-mode VCSELs by channel etching or ion implantation between the two modes. Project supported by the National Basic Research Program of China (No. 2014CB3400102), the National Natural Science Foundation of China (No. 61335004), the National High Technology Research and Development Program of China (No. 2015AA017101), and the National Key Technologies R & D Program of China (No. 2016YFB0400603).

  7. Stability study of the higher order mode beam position monitors at the Accelerating cavities at FLASH

    CERN Document Server

    Shi, L; Jones., R M

    2014-01-01

    erating cavities at FLASH linac, DESY, are equipped with electronics for beam position monitoring, which are based on HOM signals from special couplers. These monitors provide the beam position without additional vacuum components and at low cost. Moreover, they can be used to align the beam in the cavities to reduce the HOM effects on the beam. However, the HOMBPM (Higher Order Mode based Beam Position Monitor) shows an instability problem over time. In this paper, we will present the status of studies on this issue. Several methods are utilized to calibrate the HOMBPMs. These methods include DLR (Direct Linear Regression), and SVD (Singular Value Decomposition). We found that SVD generally is more suitable for HOMBPM calibration. We focus on the HOMBPMs at 1.3 GHz cavities. Techniques developed here are applicable to 3.9 ...

  8. Temporal coupled mode theory of standing wave resonant cavities for infrared photodetection.

    Science.gov (United States)

    Lesmanne, Emeline; De Lamaestre, Roch Espiau; Fowler, David; Boutami, Salim; Badano, Giacomo

    2015-03-23

    Standing wave resonating cavities have been proposed in the past to increase the performance of infrared detectors by minimizing the volume of photogeneration, hence the noise, while maintaining the same quantum efficiency. We present an approach based on the temporal coupled mode theory to explain their behavior and limitations. If the ratio of the imaginary part of the absorber's dielectric function to the index of the incident medium ε″(d)/n₀ is larger than 1.4, then the absorption cross section σ(a) can attain its maximum value, which for an isolated cavity is approximately 2λ/π. Besides, for σ(a) to exceed the cavity width, the incident medium refractive index must be close to unity. Metallic loss is negligible in the infrared, making those resonators suitable for integration in infrared photodetectors.

  9. Quantum phases and dynamics of bosonic atoms trapped in a single-mode optical cavity

    Science.gov (United States)

    Sundar, Bhuvanesh; Mueller, Erich

    2016-05-01

    Motivated by experiments performed by R. Landig et al. (arXiv:1511.00007), we theoretically explore the behavior of bosonic atoms trapped in a single-mode cavity in the presence of a two-dimensional optical lattice. As explained by arXiv:1511.00007, Rayleigh scattering of light from the lattice-inducing beams into the cavity produces infinite-range cavity-mediated interactions between the atoms, leading to competition between superfluid, supersolid, Mott insulating and charge density wave phases. We calculate the phase diagram for a uniform trap using a variation of the Gutzwiller Ansatz. We also calculate the spatial distribution of the different phases in the gas in the presence of a harmonic trap. We explore hysteretic behavior when parameters of the system are changed.

  10. Higher order mode spectra and the dependence of localized dipole modes on the transverse beam position in third harmonic superconducting cavities at FLASH

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Pei [Manchester Univ. (United Kingdom); Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Baboi, Nicoleta [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Jones, Roger M. [The Cockcroft Institute, Daresbury (United Kingdom)

    2012-06-15

    An electron beam entering an accelerating cavity excites a wakefield. This wakefield can be decomposed into a series of multi-poles or modes. The dominant component of the transverse wakefield is dipole. This report summarizes the higher order mode (HOM) signals of the third harmonic cavities of FLASH measured at various stages: transmission measurements in the single cavity test stand at Fermilab, at CMTB (Cryo- Module Test Bench) and at FLASH, and beam-excited measurements at FLASH. Modes in the first two dipole bands and the fifth dipole band have been identified using a global Lorentzian fit technique. The beam-pipe modes at approximately 4 GHz and some modes in the fifth dipole band have been observed as localized modes, while the first two dipole bands, containing some strong coupling cavity modes, propagate. This report also presents the dependence of the localized dipole modes on the transverse beam position. Linear dependence for various modes has been observed. This makes them suitable for beam position diagnostics. These modes, together with some propagating, strong coupling modes, have been considered in the design of a dedicated electronics for beam diagnostics with HOMs for the third harmonic cavities.

  11. Single-mode low threshold current multi-hole vertical-cavity surface-emitting lasers

    Institute of Scientific and Technical Information of China (English)

    Zhao Zhen-Bo; Xu Chen; Xie Yi-Yang; Zhou Kang; Liu Fa; Shen Guang-Di

    2012-01-01

    A multi-hole vertical-cavity surface-emitting laser (VCSEL) operating in stable single mode with a low threshold current was produced by introducing multi-leaf scallop holes on the top distributed Bragg-reflector of an oxidationconfined 850 nm VCSEL.The single-mode output power of 2.6 mW,threshold current of 0.6 mA,full width of half maximum lasing spectrum of less than 0.1 nm,side mode suppression ratio of 28.4 dB,and far-field divergence angle of about 10° are obtained.The effects of different hole depths on the optical characteristics are simulated and analysed,including far-field divergence,spectrum and lateral cavity mode.The single-mode performance of this multi-hole device is attributed to the large radiation loss from the inter-hole spacing and the scattering loss at the bottom of the holes,particularly for higher order modes.

  12. Single-nanoparticle detection with slot-mode photonic crystal cavities

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Cheng; Kita, Shota; Lončar, Marko, E-mail: loncar@seas.harvard.edu [School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 02138 (United States); Quan, Qimin [Rowland Institute at Harvard University, Cambridge, Massachusetts 02142 (United States); Li, Yihang [School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 02138 (United States); Department of Electronic Engineering, Tsinghua University, Beijing 100084 (China)

    2015-06-29

    Optical cavities that are capable for detecting single nanoparticles could lead to great progress in early stage disease diagnostics and the study of biological interactions on the single-molecule level. In particular, photonic crystal (PhC) cavities are excellent platforms for label-free single-nanoparticle detection, owing to their high quality (Q) factors and wavelength-scale modal volumes. Here, we demonstrate the design and fabrication of a high-Q (>10{sup 4}) slot-mode PhC nanobeam cavity, which is able to strongly confine light in the slotted regions. The enhanced light-matter interaction results in an order of magnitude improvement in both refractive index sensitivity (439 nm/RIU) and single-nanoparticle sensitivity compared with conventional dielectric-mode PhC cavities. Detection of single polystyrene nanoparticles with radii of 20 nm and 30 nm is demonstrated in aqueous environments (D{sub 2}O), without additional laser and temperature stabilization techniques.

  13. Nanotube-mode-locked linear-cavity fiber laser delivering switchable ultrafast solitons

    Science.gov (United States)

    Han, X. X.

    2015-02-01

    We propose a linear-cavity switchable fiber laser based on a single-wall carbon nanotube mode-locker for the first time to the best of our knowledge. Two chirped fiber Bragg gratings (CFBGs) in series and an optical circulator are employed as end mirrors of the linear cavity. The linear-cavity fiber laser is simple and cost-efficient. By adjusting the polarization controllers, a switchable mode-locking operation is obtained at 1551.3 and 1557.9 nm respectively, corresponding to the central wavelengths of two series-wound CFBGs. The pulse duration and spectral bandwidth of ultrafast solitons are ~4.4 ps and ~0.65 nm for the short wavelength operation at 1551.3 nm and ~3.9 ps and ~0.71 nm for the long wavelength operation at 1557.9 nm, respectively. Our experimental observations are well confirmed by the numerical results. The linear-cavity all-fiber laser reduces the cost and is very attractive for ultrafast optics.

  14. A Fast Switchyard for the TESLA FEL-Beam Using a Superconducting Transverse Mode Cavity

    CERN Document Server

    Wanzenberg, R

    2000-01-01

    In the present design of the TESLA Linear Collider with integrated X-ray Laser Facility it is necessary that 1 ms long bunch trains with about 10000 bunches are generated and distributed to several free electron laser (FEL) beam lines. The different scientific applications of the X-ray FELs need specific filling patterns of the bunches in the bunch train. It is shown that a fast switch-yard based on a superconducting transverse mode cavity can be used to generate the required bunch pattern in a flexible way while keeping the beam loading in the main linear accelerator constant. The conceptual design of the beam optics and the transverse mode cavity are presented.

  15. Validation of frequency and mode extraction calculations from time-domain simulations of accelerator cavities

    CERN Document Server

    Austin, T M; Ovtchinnikov, S; Werner, G R; Bellantoni, L

    2010-01-01

    The recently developed frequency extraction algorithm [G.R. Werner and J.R. Cary, J. Comp. Phys. 227, 5200 (2008)] that enables a simple FDTD algorithm to be transformed into an efficient eigenmode solver is applied to a realistic accelerator cavity modeled with embedded boundaries and Richardson extrapolation. Previously, the frequency extraction method was shown to be capable of distinguishing M degenerate modes by running M different simulations and to permit mode extraction with minimal post-processing effort that only requires solving a small eigenvalue problem. Realistic calculations for an accelerator cavity are presented in this work to establish the validity of the method for realistic modeling scenarios and to illustrate the complexities of the computational validation process. The method is found to be able to extract the frequencies with error that is less than a part in 10^5. The corrected experimental and computed values differ by about one parts in 10^$, which is accounted for (in largest part)...

  16. Compatibility conditions, modulation mechanisms and preferred modes in incompressible flow over a cavity

    CERN Document Server

    Delprat, Nathalie

    2010-01-01

    Self-sustained oscillations in cavity-flows can be strongly influenced by shear layer instability acting together with feedback and modulation mechanisms. When coherently organized, these oscillations lock-on at a fundamental frequency and compatibility conditions exist between shear layer forcing, non linear interactions and low-frequency modulations. Special attention is given to the frequency coincidence which may appear in spectral distributions due to combinations between the dominant peak and its sidebands. Hence, the possible existence of two preferred modes in incompressible cavity-flows at medium Reynolds numbers is shown. This leads to a detailed categorization of the flow modulated regimes and to the specification of a persistent mode involved in modulation process whatever the oscillation stage.

  17. Nanoparticle-on-mirror cavity modes for huge and/or tunable plasmonic field enhancement

    Science.gov (United States)

    Huang, Yu; Ma, Lingwei; Li, Jianghao; Zhang, Zhengjun

    2017-03-01

    We present a careful numerical study of nanoparticle (NP) faceting, highlighting the great influence of small morphological changes of NP-mirror cavities on near-field enhancement in the nanoparticle-on-mirror (NPOM) system. Using a 3D finite element method (FEM) plasmon mapping method, the active transverse cavity modes can be confirmed. For the dominant mode, we have found that, by increasing the facet width, the resonance can be tuned linearly to the red with little decrease of the peak near-field intensity. It is further demonstrated that by increasing the NP size, the near-field intensity can be strongly enhanced. Understanding of such extreme optics benefits significantly both the optimized design of potential plasmonic devices and the fundamental understanding of nano-optics. Collaborative experimental considerations are expected with the rapid development of nanotechnology.

  18. Modeling and optimization of single-mode vertical cavity surface emitting lasers

    Science.gov (United States)

    Dahiya, Sandeep; Kumar, Suresh; Kaushik, Brajesh Kumar

    2016-10-01

    Vertical cavity surface emitting laser (VCSEL) plays a vital role in optical network. The present investigation reports the performance comparison of the modeling of single-mode VCSELs at room temperature for continuous wave operation. VCSEL for the study consists of InGaAsP-based cavity or active region sandwiched between GaAs/AlGaAs top mirror and GaAs/AlAs bottom mirrors with the aim of increasing the power conversion efficiency (PCE), lasing power, and decreasing the threshold current. It is observed that VCSELs with lower diameter are most suitable to achieve energy-efficient operation. The PCE obtained is ˜50% for the proposed single-mode VCSELs. The proposed VCSELs are suitable for short-reach optical interconnects such as chip-to-chip and board-to-board communication in high-performance computers.

  19. Flow coherent structures and frequency signature: application of the dynamic modes decomposition to open cavity flow

    Energy Technology Data Exchange (ETDEWEB)

    Lusseyran, F; Gueniat, F; Basley, J; Douay, C L; Pastur, L R; Faure, T M [LIMSI-CNRS BP 133, F-91403 Orsay Cedex (France); Schmid, P J [LadHyX, Ecole Polytechnique, F-91128 Palaiseau (France)

    2011-12-22

    The dynamic dimension of an impinging flow may be significantly reduced by its boundary conditions and self-sustained oscillations they induce. The spectral signature is associated with remarkable spatial coherent structures. Dynamic modes decomposition (DMD) makes it possible to directly extract the dynamical properties of a non-linearly saturated flow. We apply DMD to highlight the spectral contribution of the longitudinal and transverse structures of an experimental open-cavity flow.

  20. Optimizing of the higher order mode dampers in the 56MHz SRF cavity

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Q.; Ben-Zvi, I.

    2010-01-27

    Earlier, we reported that a 56 MHz cavity was designed for a luminosity upgrade of the RHIC, and presented the requirements for Higher Order Mode (HOM) damping, the design of the HOM dampers, along with measurements and simulations of the HOM dampers. In this report, we describe our optimization of the dampers performance, and the modifications we made to their original design. We also optimized the number of the HOM dampers, and tested different configurations of locations for them.

  1. Fermilab 500 GeV main accelerator rf cavity 128 MHz mode damper

    Energy Technology Data Exchange (ETDEWEB)

    Kerns, Q.A.; Miller, H.W.

    1977-01-01

    The Fermilab 500-GeV main accelerating system has been operating for a year now with the aid of 128-MHz mode dampers. Such dampers proved to be necessary to achieve stable operation and a reasonably smooth slow spill at intensities of approximately 2 x 10/sup 13/ protons per pulse, and furthermore are low-cost and reliable. The approach used to identify troublesome modes, the observed beam blow-up without dampers, and the steps taken to design and install suitable dampers on eighteen main ring cavities are discussed. Spectrum analyzer pictures help illustrate the performance.

  2. Effect of mean flow on the trapped modes of internal cavities

    Science.gov (United States)

    Aly, Kareem; Ziada, Samir

    2012-08-01

    Flow-excited acoustic resonance of trapped modes in ducts has been reported in different engineering applications. The excitation mechanism of these modes results from the interaction between the hydrodynamic flow field and the acoustic particle velocity, and is therefore dependent on the mode shape of the resonant acoustic field, including the amplitude and phase distributions of the acoustic particle velocity. This paper investigates numerically the effect of mean flow on the characteristics of the resonant trapped modes for a cavity-duct system, which is known to generate strong resonances at moderate Mach numbers. The numerical simulations are performed for two dimensional planar and three dimensional axisymmetric geometries at different flow Mach numbers up to 0.3. A two-step numerical scheme is adopted in which the mean flow is solved in the first step, and in the second step a system of linearized acoustic perturbation equations is used to predict the acoustic field. Comparison of the results with the available experimental data illustrates that the current approach can predict accurately the dependence of the trapped mode frequency on the mean flow Mach number. More importantly, as the Mach number is increased, the acoustic pressure is observed to develop an axial phase gradient and the amplitude and phase distributions of the acoustic particle velocity are found to change significantly near the cavity shear layer. These results demonstrate the importance of considering the effects of the mean flow on the flow-sound interaction mechanism.

  3. Novel Geometries for the LHC Crab Cavity

    Energy Technology Data Exchange (ETDEWEB)

    Hall, B. [Lancaster Univ. (United Kingdom); Burt, G. [Lancaster Univ. (United Kingdom); Smith, J. D.A. [Lancaster Univ. (United Kingdom); Rimmer, R. [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Wang, H. [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Delayen, J. [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Calaga, R. [Brookhaven National Lab. (BNL), Upton, NY (United States)

    2009-05-01

    In 2017 the LHC is envisioned to increase its luminosity via an upgrade. This upgrade is likely to require a large crossing angle hence a crab cavity is required to align the bunches prior to collision. There are two possible schemes for crab cavity implementation, global and local. In a global crab cavity the crab cavity is far from the IP and the bunch rotates back and forward as it traverses around the accelerator in a closed orbit. For this scheme a two-cell elliptical squashed cavity at 800 MHz is preferred. To avoid any potential beam instabilities all the parasitic modes of the cavities must be damped strongly, however crab cavities have lower order and same order modes in addition to the usual higher order modes and hence a novel damping scheme must be used to provide sufficient damping of these modes. In the local scheme two crab cavities are placed at each side of the IP two start and stop rotation of the bunches. This would require crab cavities much smaller transversely than in the global scheme but the frequency cannot be increased any higher due to the long bunch length of the LHC beam. This will require a novel compact crab cavity design. A superconducting version of a two rod coaxial deflecting cavity as a suitable design is proposed in this paper.

  4. Dynamics of a broad-area diode laser with lateral-mode-selected long-cavity feedback

    DEFF Research Database (Denmark)

    Chi, Mingjun; Petersen, Paul Michael

    2014-01-01

    of the cases, the output of the laser shows a periodic oscillation corresponding to a single roundtrip external-cavity loop, but the dynamic behavior disappears in some case; when the zero-order lateral-mode is selected, periodic oscillation corresponding to a double roundtrip external-cavity loop is observed....... When the feedback mirror is aligned non-perfectly, pulse-package oscillation is observed, for the first time to our knowledge, in a diode laser with long-cavity feedback....

  5. Optical characterization and selective addressing of the resonant modes of a micropillar cavity with a white light beam

    NARCIS (Netherlands)

    Ctistis, Georgios; Hartsuiker, Alex; Pol, van der Edwin; Claudon, Julien; Vos, Willem L.; Gérard, Jean-Michel

    2010-01-01

    We have performed white light reflectivity measurements on GaAs/AlAs micropillar cavities with diameters ranging from 1 μm up to 20 μm. We are able to resolve the spatial field distribution of each cavity mode in real space by scanning a small-sized beam across the top facet of each micropillar. We

  6. Unconventional Geometric Phase-Shift Gates Based on Superconducting Quantum Interference Devices Coupled to a Single-Mode Cavity

    Institute of Scientific and Technical Information of China (English)

    SONG Ke-Hui; ZHOU Zheng-Wei; GUO Guang-Can

    2006-01-01

    We present a scheme to realize geometric phase-shift gate for two superconducting quantum interference device (SQUID) qubits coupled to a single-mode microwave field. The geometric phase-shift gate operation is performed transitions during the gate operation. Thus, the docoherence due to energy spontaneous emission based on the levels of SQUIDs are suppressed. The gate is insensitive to the cavity decay throughout the operation since the cavity mode is displaced along a circle in the phase space, acquiring a phase conditional upon the two lower flux states of the SQUID qubits, and the cavity mode is still in the original vacuum state. Based on the SQUID qubits interacting with the cavity mode, our proposed approach may open promising prospects for quantum logic in SQUID-system.

  7. Split-disk micro-lasers: Tunable whispering gallery mode cavities

    Directory of Open Access Journals (Sweden)

    T. Siegle

    2017-09-01

    Full Text Available Optical micro-cavities of various types have emerged as promising photonic structures, for both the investigation of fundamental science in cavity quantum electrodynamics and simultaneously for various applications, e.g., lasers, filters, or modulators. In either branch a demand for adjustable and tunable photonic devices becomes apparent, which has been mainly based on the modification of the refractive index of the micro-resonators so far. In this paper, we report on a novel type of whispering gallery mode resonator where resonance tuning is achieved by modification of the configuration. This is realized by polymeric split-disks consisting of opposing half-disks with an intermediate air gap. Functionality of the split-disk concept and its figures of merit like low-threshold lasing are demonstrated for laser dye-doped split-disks fabricated by electron beam lithography on Si substrates. Reversible resonance tuning is achieved for split-disks structured onto elastomeric substrates by direct laser writing. The gap width and hence the resonance wavelength can be well-controlled by mechanically stretching the elastomer and exploiting the lateral shrinkage of the substrate. We demonstrate a broad spectral tunability of laser modes by more than three times the free spectral range. These cavities have the potential to form a key element of flexible and tunable photonic circuits based on polymers.

  8. Split-disk micro-lasers: Tunable whispering gallery mode cavities

    Science.gov (United States)

    Siegle, T.; Remmel, M.; Krämmer, S.; Kalt, H.

    2017-09-01

    Optical micro-cavities of various types have emerged as promising photonic structures, for both the investigation of fundamental science in cavity quantum electrodynamics and simultaneously for various applications, e.g., lasers, filters, or modulators. In either branch a demand for adjustable and tunable photonic devices becomes apparent, which has been mainly based on the modification of the refractive index of the micro-resonators so far. In this paper, we report on a novel type of whispering gallery mode resonator where resonance tuning is achieved by modification of the configuration. This is realized by polymeric split-disks consisting of opposing half-disks with an intermediate air gap. Functionality of the split-disk concept and its figures of merit like low-threshold lasing are demonstrated for laser dye-doped split-disks fabricated by electron beam lithography on Si substrates. Reversible resonance tuning is achieved for split-disks structured onto elastomeric substrates by direct laser writing. The gap width and hence the resonance wavelength can be well-controlled by mechanically stretching the elastomer and exploiting the lateral shrinkage of the substrate. We demonstrate a broad spectral tunability of laser modes by more than three times the free spectral range. These cavities have the potential to form a key element of flexible and tunable photonic circuits based on polymers.

  9. Doubly-Resonant Fabry-Perot Cavity for Power Enhancement of Burst-Mode Picosecond Ultraviolet Pulses

    Energy Technology Data Exchange (ETDEWEB)

    Abudureyimu, Reheman [ORNL; Huang, Chunning [ORNL; Liu, Yun [ORNL

    2015-01-01

    We report on a first experimental demonstration of locking a doubly-resonant Fabry-Perot cavity to burst-mode picosecond ultraviolet (UV) pulses by using a temperature controlled dispersion compensation method. This technique will eventually enable the intra cavity power enhancement of burst-mode 402.5MHz/50ps UV laser pulses with a MW level peak power required for the laser assisted H- beam stripping experiment at the Spallation Neutron Source.

  10. Dark-field imaging as a non-invasive method for characterization of whispering gallery modes in microdisk cavities

    CERN Document Server

    Baranov, D A; Shishkin, I I; Samusev, A K; Belov, P A; Bogdanov, A A

    2016-01-01

    Whispering gallery mode microdisk cavities fabricated by direct laser writing are studied using dark-field imaging and spectroscopy in the visible spectral range. {Dark-field imaging allows us to directly visualize the spatial intensity distribution of whispering gallery modes. We extract their azimuthal and radial mode indices from dark-field images, and find the axial mode number from the dispersion relation. The scattering spectrum obtained in the confocal arrangement provides information on the density of optical states in the resonator. The proposed technique is a simple non-invasive way to characterize the optical properties of microdisk cavities.

  11. Intensity modulation in single-mode microchip Nd:YAG lasers with asymmetric external cavity

    Institute of Scientific and Technical Information of China (English)

    Tan Yi-Dong; Zhang Shu-Lian; Liu Wei-Xin; Mao Wei

    2007-01-01

    Intensity modulation induced by the asymmetric external cavity in single-mode microchip Nd:YAG lasers is presented. Two kinds of experimental results are discussed based on multiple feedback effects. In one case, the intensity modulation curve is a normal sine wave, whose fringe frequency is four times higher than that of a conventional optical feedback system, caused by multiple feedback effects. In the other case, the intensity modulation curve is the overlapping of the above quadruple-frequency signal and conventional optical feedback signal, which is determined by the additional phase difference induced by the asymmetric external cavity. The theoretical analyses are in good agreement with the experimental results. The quadruple-frequency modulation of the laser output intensity can greatly increase the resolution of displacement measurement of an optical feedback system.

  12. Intra-cavity frequency-doubled mode-locked semiconductor disk laser at 325 nm.

    Science.gov (United States)

    Bek, Roman; Baumgärtner, Stefan; Sauter, Fabian; Kahle, Hermann; Schwarzbäck, Thomas; Jetter, Michael; Michler, Peter

    2015-07-27

    We present a passively mode-locked semiconductor disk laser (SDL) emitting at 650nm with intra-cavity second harmonic generation to the ultraviolet (UV) spectral range. Both the gain and the absorber structure contain InP quantum dots (QDs) as active material. In a v-shaped cavity using the semiconductor samples as end mirrors, a beta barium borate (BBO) crystal is placed in front of the semiconductor saturable absorber mirror (SESAM) for pulsed UV laser emission in one of the two outcoupled beams. Autocorrelation (AC) measurements at the fundamental wavelength reveal a FWHM pulse duration of 1.22ps. With a repetition frequency of 836MHz, the average output power is 10mW per beam for the red emission and 0.5mW at 325nm.

  13. Effect of cavity length on low-energy single longitudinal mode pre-lase Q-switched laser

    Science.gov (United States)

    Qing-Song, Li; Yuan, Dong; Yu, Liu; Xi-He, Zhang; Yong-Ji, Yu; Guang-Yong, Jin

    2017-09-01

    In this paper, the effect of cavity length on a low-energy single longitudinal mode (SLM) pre-lase Q-switched laser is analyzed and demonstrated. Taking a Pr:YLF laser as an example, the basic output characteristics under pre-lase technology are shown. The SLM is degraded when the cavity length is as large as 25 mm. Further, for cavity lengths of 15 or 20 mm, SLM is achieved with different output characteristics. Compared with a long cavity (20 mm), the short-cavity case (15 mm) is indeed helpful for obtaining an SLM laser; however, the single-pulse energy, pulse width, and energy extraction efficiency are decreased by 4.7, 48, and 6.7%, respectively. The results of this analysis show that the cavity length influences the output characteristics and determines the realization of SLM in a pre-lase Q-switched laser. This is because the short cavity induces a relatively strong gain identification for the seed signal. Then, the time cost of the mode competition decreases and SLM can be achieved easily. However, a long cavity is conducive to mode competition, which generates superior output characteristics.

  14. Q-switched mode-locking of an erbium-doped fiber laser using cavity modulation frequency detuning.

    Science.gov (United States)

    Chang, You Min; Lee, Junsu; Jhon, Young Min; Lee, Ju Han

    2012-07-20

    We present the results of an investigation regarding a Q-switched mode-locked fiber laser scheme based on a cavity modulation frequency detuning technique. The approach is based on undamped laser relaxation oscillations occurring due to frequency detuning in the fundamental cavity resonance frequency. Through a range of experiments with an erbium-doped, fiber-based, ring-cavity laser, this approach has been shown to be capable of generating high-quality Q-switched mode-locked pulses from an optical fiber-based laser. The maximum frequency detuning range for a stable Q-switched mode-locking operation has been observed to vary depending on the pump power used. We found that the highest pulse peak power was obtained at the frequency detuning threshold at which the operation changed from the mode-locking to the Q-switched mode-locking regime.

  15. Analysis of the hot-cavity mode composition of an X-band overmoded relativistic backward wave oscillators

    Science.gov (United States)

    Yuan, Yuzhang; Zhang, Jun; Zhong, Huihuang; Zhang, Dian

    2016-07-01

    Overmoded RBWO (Relativistic Backward Wave Oscillators) is utilized more and more often for its high power capacity. However, both sides of SWS (Slow Wave Structure) of overmoded RBWO consist multi TM0n modes; in order to achieve the design of reflector, it is essential to make clear of the mode composition of TM0n. NUDT (National University of Defence Technology) had done research of the output mode composition in overmoded O-type Cerenkov HPM (High Power Microwave) Oscillators in detail, but in the area where the electron beam exists, the influence of electron beam must be taken into account. Hot-cavity dispersion equation is figured out in this article first, and then analyzes the hot-cavity mode composition of an X-band overmoded RBWO tentatively. The results show that in collimating hole, the hot-cavity mode analysis is more accurate.

  16. A case study testing the cavity mode model of the magnetosphere

    Directory of Open Access Journals (Sweden)

    D. V. Sarafopoulos

    2005-07-01

    Full Text Available Based on a case study we test the cavity mode model of the magnetosphere, looking for eigenfrequencies via multi-satellite and multi-instrument measurements. Geotail and ACE provide information on the interplanetary medium that dictates the input parameters of the system; the four Cluster satellites monitor the magnetopause surface waves; the POLAR (L=9.4 and LANL 97A (L=6.6 satellites reveal two in-situ monochromatic field line resonances (FLRs with T=6 and 2.5 min, respectively; and the IMAGE ground magnetometers demonstrate latitude dependent delays in signature arrival times, as inferred by Sarafopoulos (2004b. Similar dispersive structures showing systematic delays are also extensively scrutinized by Sarafopoulos (2005 and interpreted as tightly associated with the so-called pseudo-FLRs, which show almost the same observational characteristics with an authentic FLR. In particular for this episode, successive solar wind pressure pulses produce recurring ionosphere twin vortex Hall currents which are identified on the ground as pseudo-FLRs. The BJN ground magnetometer records the pseudo-FLR (alike with the other IMAGE station responses associated with an intense power spectral density ranging from 8 to 12 min and, in addition, two discrete resonant lines with T=3.5 and 7 min. In this case study, even though the magnetosphere is evidently affected by a broad-band compressional wave originated upstream of the bow shock, nevertheless, we do not identify any cavity mode oscillation within the magnetosphere. We fail, also, to identify any of the cavity mode frequencies proposed by Samson (1992.

    Keywords. Magnetospheric physics (Magnetosphereionosphere interactions; Solar wind-magnetosphere interactions; MHD waves and instabilities

  17. Electron Bunch Train Excited Higher-Order Modes in a Superconducting RF Cavity

    CERN Document Server

    Gao, Yongfeng; Wang, Fang; Feng, Liwen; Zhuang, Dehao; Lin, Lin; Zhu, Feng; Hao, Jiankui; Quan, Shengwen; Liu, Kexin

    2016-01-01

    Higher-order mode (HOM) based intra-cavity beam diagnostics has been proved effectively and conveniently in superconducting radio-frequency (SRF) accelerators. Our recent research shows that the beam harmonics in the bunch train excited HOM spectrum, which have much higher signal-to-noise ratio than the intrinsic HOM peaks, may also be useful for beam diagnostics. In this paper, we will present our study on bunch train excited HOMs, including the theoretic model and recent experiments carried out based on the DC-SRF photoinjector and SRF linac at Peking University.

  18. Investigation of Fano resonances induced by higher order plasmon modes on a circular nano-disk with an elongated cavity

    KAUST Repository

    Amin, Muhammad Ruhul

    2012-08-10

    In this paper, a planar metallic nanostructure design, which supports two distinct Fano resonances in its extinction cross-section spectrum under normally incident and linearly polarized electromagnetic field, is proposed. The proposed design involves a circular disk embedding an elongated cavity; shifting and rotating the cavity break the symmetry of the structure with respect to the incident field and induce higher order plasmon modes. As a result, Fano resonances are generated in the visible spectrum due to the destructive interference between the sub-radiant higher order modes and super-radiant the dipolar mode. The Fano resonances can be tuned by varying the cavity\\'s width and the rotation angle. An RLC circuit, which is mathematically equivalent to a mass-spring oscillator, is proposed to model the optical response of the nanostructure design.

  19. On The Anomalous Fast Ion Energy Diffusion in Toroidal Plasmas Due to Cavity Modes

    Energy Technology Data Exchange (ETDEWEB)

    N.N. Gorelenkov, N.J. Fisch and E. Fredrickson

    2010-03-09

    An enormous wave-particle diffusion coefficient along paths suitable for alpha channeling had been deduced in mode converted ion Bernstein wave experiments on Tokamak Fusion Test Reactor (TFTR) the only plausible explanation advanced for such a large diffusion coefficient was the excitation of internal cavity modes which induce particle diffusion along identical diffusion paths, but at much higher rates. Although such a mode was conjectured, it was never observed. However, recent detailed observations of high frequency compressional Alfven eigenmodes (CAEs) on the National Spherical torus Experiment (NSTX) indirectly support the existence of the related conjectured modes on TFTR. The eigenmodes responsible for the high frequency magnetic activity can be identified as CAEs through the polarization of the observed magnetic field oscillations in NSTX and through a comparison with the theoretically derived freuency dispersion relation. Here, we show how these recent observations of high frequency CAEs lend support to this explanation of the long-standing puzzle of anomalous fast ion energy diffusion on TFTR. The support of the conjecure that these internal modes could have caused the remarkable ion energy diffusion on TFTR carries significant and favorable implications for the possibilities in achieving the alpha channeling effect with small injected power in a tokamak reactor.

  20. Cavity ring-up spectroscopy for dissipative and dispersive sensing in a whispering gallery mode resonator

    CERN Document Server

    Yang, Yong; Kasumie, Sho; Ward, Jonathan M; Chormaic, Síle Nic

    2016-01-01

    In whispering gallery mode resonator sensing applications, the conventional way to detect a change in the parameter to be measured is by observing the steady state transmission spectrum through the coupling waveguide. Alternatively, cavity ring-up spectroscopy (CRUS) sensing can be achieved transiently. In this work, we investigate CRUS using coupled mode equations and find analytical solutions with a large spectral broadening approximation of the input pulse. The relationships between the frequency detuning, coupling gap and ring-up peak height are determined and experimentally verified using an ultrahigh \\textit{Q}-factor silica microsphere. This work shows that distinctive dispersive and dissipative transient sensing can be realised by simply measuring the peak height of the CRUS signal, which might improve the data collection rate.

  1. Coexistence of Scattering Enhancement and Suppression by Plasmonic Cavity Modes in Loaded Dimer Gap-Antennas

    CERN Document Server

    Zhang, Qiang; Li, Meili; Han, Dezhuan; Gao, Lei

    2015-01-01

    Plasmonic nanoantenna is of promising applications in optical sensing, single-molecular detection, and enhancement of optical nonlinear effect, surface optical spectroscopy, photochemistry, photoemission, photovoltaics, etc. Here we show that in a carefully-designed dimer gap-antenna made by two metallic nanorods, the longitudinal plasmon antenna mode (AM) of bonding dipoles can compete with the transverse plasmonic cavity modes (CMs), yielding dramatically enhanced or suppressed scattering efficiency, depending on the CMs symmetry characteristics (e.g., the radial order n and the azimuthal quantum number m ). More specifically, it is demonstrated that an appropriately loaded gap layer enables substantial excitation of toroidal moment and its strong interaction with the AM dipole moment, resulting in Fano- or electromagnetically induced transparency (EIT)-like profile in the scattering spectrum. However, for CMs with nonzero azimuthal number, the spectrum features a cumulative signature of the respective AM a...

  2. Study Pulse Parameters versus Cavity Length for Both Dispersion Regimes in FM Mode Locked

    Directory of Open Access Journals (Sweden)

    Bushra Razooky Mhdi

    2015-03-01

    Full Text Available To demonstrate the effect of changing cavity length for  FM mode locked on pulse parameters and make comparison for both dispersion regime , a plot for each pulse parameter as Lr function are presented for normal and anomalous dispersion regimes. The analysis is based on the theoretical study and the results of numerical simulation using MATLAB. The effect of both normal and anomalous dispersion regimes on output pulses is investigate Fiber length effects on pulse parameters are investigated by driving the modulator into different values. A numerical solution for model equations using fourth-fifth order, Runge-Kutta method is performed through MATLAB 7.0 program. Fiber length effect on pulse parameters is investigated by driving the modulator into different values of lengths. Result shows that, the output pulse width from the FM mode locked equals to τ= 501ns anomalous regime and τ=518ns in normal regime.

  3. Component mode synthesis and large deflection vibration of complex structures. Volume 3: Multiple-mode nonlinear free and forced vibrations of beams using finite element method

    Science.gov (United States)

    Mei, Chuh; Shen, Mo-How

    1987-01-01

    Multiple-mode nonlinear forced vibration of a beam was analyzed by the finite element method. Inplane (longitudinal) displacement and inertia (IDI) are considered in the formulation. By combining the finite element method and nonlinear theory, more realistic models of structural response are obtained more easily and faster.

  4. Effects of spanwise instabilities on the suppression of wake mode in flow over a long rectangular cavity

    Science.gov (United States)

    Sun, Yiyang; Taira, Kunihiko; Cattafesta, Louis; Ukeiley, Lawrence

    2016-11-01

    Direct numerical simulation (DNS) and biglobal stability analysis are performed to examine the spanwise effects on the appearance of the so-called wake mode in the flow over long rectangular cavities. The wake mode has been reported to exhibit high-amplitude fluctuations and eject large spanwise vortices in numerical studies, despite its lack of observation in experiments, leaving its existence an open question. The present study focuses on a rectangular cavity flow with aspect ratio of L / D = 6 , free stream Mach number of M∞ = 0 . 6 and ReD = 502 . The properties of the wake mode are revealed via 2D DNS. From the biglobal stability analysis, the wake mode can be captured with a zero spanwise wavenumber. Furthermore, 3D eigenmodes are calculated with spanwise wavelength λ / D ∈ [ 0 . 5 , 2 ] . With the knowledge of the features of the wake mode and the 3D eigenmodes, 3D DNS are performed with width-to-depth ratio of W / D = 1 and 2. We find the flow exhibits the wake mode with W / D = 1 but presents a moderate shear-layer mode with W / D = 2 . Based on the findings, we argue that the spanwise instabilities in flows over wide cavities redistribute energy from spanwise vortices to streamwise vortical structures, which suppresses the emergence of the wake mode in the 3D cavity flows. This work was supported by the US Air Force Office of Scientific Research (Grant FA9550-13-1-0091).

  5. Cavity Mode Related Wire Breaking of the SPS Wire Scanners and Loss Measurements of Wire Materials

    CERN Document Server

    Caspers, Friedhelm; Jensen, E; Koopman, J; Malo, J F; Roncarolo, F

    2003-01-01

    During the SPS high intensity run 2002 with LHC type beam, the breaking of several of the carbon wires in the wire scanners has been observed in their parking position. The observation of large changes in the wire resistivity and thermionic electron emission clearly indicated strong RF heating that was depending on the bunch length. A subsequent analysis in the laboratory, simulating the beam by two probe antennas or by a powered stretched wire, showed two main problems: i) the housing of the wire scanner acts as a cavity with a mode spectrum starting around 350 MHz and high impedance values around 700 MHz; ii) the carbon wire used so far appears to be an excellent RF absorber and thus dissipates a significant part of the beam-induced power. Different wire materials are compared with the classical cavity mode technique for the determination of the complex permittivity in the range of 2-4 GHz. As a resonator a rectangular TE_01n type device is utilized.

  6. Cavity mode related wire breaking of the SPS Wire Scanners and loss measurements of wire materials

    CERN Document Server

    Roncarolo, Federico

    2003-01-01

    During the SPS high intensity run 2002 with LHC type beam, the breaking of several of the carbon wires in the wire scanners has been observed in their parking position. The observation of large changes in the wire resistivity and thermionic electron emission clearly indicated strong RF heating that was depending on the bunch length. A subsequent analysis in the laboratory, simulating the beam by two probe antennas or by a powered stretched wire, showed two main problems: i) the housing of the wire scanner acts as a cavity with a mode spectrum starting around 350MHz and high impedance values around 700 MHz; ii) the carbon wire used so far appears to be an excellent RF absorber and thus dissipates a significant part of the beam-induced power. Different wire materials are compared with the classical cavity mode technique for the determination of the complex permittivity in the range of 2-4 GHz. As a resonator a rectangular TE01n type device is utilized.

  7. An ultra-narrow-band optical filter based on whispering-gallery-mode hybrid-microsphere-cavity

    Science.gov (United States)

    Wan, Hongdan; Zhu, Haohan; Liu, Linqian; Xu, Ji; Wang, Jin

    2016-10-01

    We demonstrate an ultra-narrow-band mode-selection method based on a hybrid-microsphere-cavity which consists of a coated silica microsphere. Optical field distribution and narrow-band transmission spectrum of the whispering gallery modes (WGM) are investigated by finite-difference time-domain method. WGM transmission spectra are measured for microsphere and tapered fibers with different diameters. A high refractive index layer coated on the microsphere-cavity make the Q factor increased, the transmission spectrum bandwidth compressed and the side-mode suppression ratio increased. Parameters of the hybrid-microsphere-cavity, namely, the coated shell thickness and its refractive index are optimized under different excitation light source as to investigate the whispering-gallery-modes' transmission spectrum. The 3dB bandwidth of the proposed filter can be less than MHz which will have great potential for applications in all-optical sensing and communication systems.

  8. Mode-locking optimization with a real-time feedback system in a Nd:yttrium lithium fluoride laser cavity

    Science.gov (United States)

    Marengoni, C.; Canova, F.; Batani, D.; Benocci, R.; Librizzi, M.; Narayanan, V.; Gomareschi, M.; Lucchini, G.; Kilpio, A.; Shashkov, E.; Stuchebrukhov, I.; Vovchenko, V.; Chernomyrdin, V.; Krasuyk, I.; Hall, T.; Bittanti, S.

    2007-01-01

    We present a control system, which allows an automatic optimization of the pulse train stability in a mode-locked laser cavity. In order to obtain real-time corrections, we chose a closed loop approach. The control variable is the cavity length, mechanically adjusted by gear system acting on the rear cavity mirror, and the controlled variable is the envelope modulation of the mode-locked pulse train. Such automatic control system maintains the amplitude of the mode-locking pulse train stable within a few percent rms during the working time of the laser. Full implementation of the system on an Nd:yttrium lithium fluoride actively mode-locked laser is presented.

  9. Generation of Two-Mode Nonclassical States via Dispersive Interaction in Trapped-Ion Cavity Quantum Electrodynamics

    Institute of Scientific and Technical Information of China (English)

    YANG Wen-Xing; ZHAN Zhi-Ming; LI Jia-Hua

    2004-01-01

    @@ We propose a simple method to generate a practical SU(2)-Schrodinger-cat state of a single trapped-ion vibration mode and the light field state, using the method based on a quantum system, which is composed of the onedimensional trapped-ion motion and a single cavity field mode. Moreover, the method proposed can be used for the generation two-mode maximal quantum entangled state. The detection of such a state is also briefly discussed.

  10. ELECTROMAGNETIC FIELD MEASUREMENT OF FUNDAMENTAL AND HIGHER-ORDER MODES FOR 7-CELL CAVITY OF PETRA-II

    Energy Technology Data Exchange (ETDEWEB)

    Kawashima, Y.; Blednykh, A.; Cupolo, J.; Davidsaver, M.; Holub, B.; Ma, H.; Oliva, J.; Rose, J.; Sikora, R.; Yeddulla, M.

    2011-03-28

    The booster synchrotron for NSLS-II will include a 7-cell PETRA cavity, which was manufactured for the PETRA-II project at DESY. The cavity fundamental frequency operates at 500 MHz. In order to verify the impedances of the fundamental and higher-order modes (HOM), which were calculated by computer code, we measured the magnitude of the electromagnetic field of the fundamental acceleration mode and HOM using the bead-pull method. To keep the cavity body temperature constant, we used a chiller system to supply cooling water at 20 degrees C. The bead-pull measurement was automated with a computer. We encountered some issues during the measurement process due to the difficulty in measuring the electromagnetic field magnitude in a multi-cell cavity. We describe the method and apparatus for the field measurement, and the obtained results.

  11. Quantum atomic lithography via cross-cavity optical Stern-Gerlach setup

    Science.gov (United States)

    Máximo, C. E.; Batalhão, T. B.; Bachelard, R.; de Moraes Neto, G. D.; de Ponte, M. A.; Moussa, M. H. Y.

    2014-10-01

    We present a fully quantum scheme to perform 2D atomic lithography based on a cross-cavity optical Stern-Gerlach setup: an array of two mutually orthogonal cavities crossed by an atomic beam perpendicular to their optical axes, which is made to interact with two identical modes. After deriving an analytical solution for the atomic momentum distribution, we introduce a protocol allowing us to control the atomic deflection by manipulating the amplitudes and phases of the cavity field states.

  12. High-power single-mode vertical-cavity surface-emitting lasers

    Science.gov (United States)

    Samal, Nigamananda

    High-power single-mode vertical-cavity surface-emitting lasers (VCSEL) have a great potential to replace the distributed feedback (DFB) and Fabry-Perot (FP) edge emitting lasers that are currently used in optical communication. VCSELs also have tremendous potential in many niche applications such as "optical read and write," laser printing, bar code scanning and sensing. Despite many of their inherent advantages over its rivals, VCSELs still suffer from some outstanding issues. Most prominent are "limited power" and "multi-mode behavior" at higher injection. This work aims at a few solutions for these fundamental issues. Using strain-compensated GaAsSb as an active material and a standard single-aperture design, 1.3 mum VCSELs are demonstrated and characterized. These devices face basic issues such as "limited output power" and "multi-mode behavior." These VCSELs achieved room temperature CW operation with power outputs from 50--200 muW for wavelengths ranging from 1245 to 1290 nm. To resolve the issue of limited power, several on-wafer thermal-management schemes are proposed. One of the schemes is pursued in this work. To resolve the issue of multi-mode behavior, a novel device design using asymmetric double oxide-apertures is proposed, theoretically modeled, and implemented in this work. The optical mode behavior of this novel design is compared with a traditional single-aperture design using fabricated devices and theoretical modeling. A clear trend of spectral purity in the modal behavior of the devices, under both continuous wave (CW) and pulsed conditions, is demonstrated and is in good agreement with theoretical predictions. One of the novel designs tested on an InGaAs VCSEL has shown a multi-mode power more than 23 mW with maximum wall plug efficiency of 32%, threshold current of 2.5 mA, threshold voltage of 1.2 V, and a slope efficiency of 0.83 W/A. The best design demonstrated a room temperature CW single-mode output power of more than 7 mW with a side

  13. Measurement of the high-field Q drop in the TM010 and TE011 modes in a niobium cavity

    Energy Technology Data Exchange (ETDEWEB)

    Gianluigi Ciovati; Peter Kneisel

    2006-04-01

    In the last few years superconducting radio-frequency (rf) cavities made of high-purity (residual resistivity ratio>200) niobium achieved accelerating gradients close to the theoretical limits. An obstacle towards achieving reproducibly higher fields is represented by ''anomalous'' losses causing a sharp degradation of the cavity quality factor when the peak surface magnetic field (Bp) is above about 90 mT, in the absence of field emission. This effect, called ''Q drop'' has been measured in many laboratories with single- and multicell cavities mainly in the gigahertz range. In addition, a low-temperature (100-140 C) ''in situ'' baking of the cavity was found to be beneficial in reducing the Q drop. In order to gain some understanding of the nature of these losses, a single-cell cavity has been tested in the TM010 and TE011 modes at 2 K. The feature of the TE011 mode is to have zero electric field on the cavity surface, so that electric field effects can be excluded as a source for the Q drop. This article will present some of the experimental results for different cavity treatments and will compare them with existing models.

  14. Modulating resonance modes and Q value of a CdS nanowire cavity by single Ag nanoparticles.

    Science.gov (United States)

    Zhang, Qing; Shan, Xin-Yan; Feng, Xiao; Wang, Chun-Xiao; Wang, Qu-Quan; Jia, Jin-Feng; Xue, Qi-Kun

    2011-10-12

    Semiconductor nanowire (NW) cavities with tailorable optical modes have been used to develop nanoscale oscillators and amplifiers in microlasers, sensors, and single photon emitters. The resonance modes of NW could be tuned by different boundary conditions. However, continuously and reversibly adjusting resonance modes and improving Q-factor of the cavity remain a great challenge. We report a method to modulate resonance modes continuously and reversibly and improve Q-factor based on surface plasmon-exciton interaction. By placing single Ag nanoparticle (NP) nearby a CdS NW, we show that the wavelength and relative intensity of the resonance modes in the NW cavity can systematically be tuned by adjusting the relative position of the Ag NP. We further demonstrate that a 56% enhancement of Q-factor and an equivalent π-phase shift of the resonance modes can be achieved when the Ag NP is located near the NW end. This hybrid cavity has potential applications in active plasmonic and photonic nanodevices.

  15. Core-Shell Structured Dielectric-Metal Circular Nanodisk Antenna: Gap Plasmon Assisted Magnetic Toroid-like Cavity Modes

    CERN Document Server

    Zhang, Qiang; Zhang, Xiao Ming; Han, Dezhuan; Gao, Lei

    2014-01-01

    Plasmonic nanoantennas, the properties of which are essentially determined by their resonance modes, are of interest both fundamentally and for various applications. Antennas with various shapes, geometries and compositions have been demonstrated, each possessing unique properties and potential applications. Here, we propose the use of a sidewall coating as an additional degree of freedom to manipulate plasmonic gap cavity modes in strongly coupled metallic nanodisks. It is demonstrated that for a dielectric middle layer with a thickness of a few tens of nanometers and a sidewall plasmonic coating of more than ten nanometers, the usual optical magnetic resonance modes are eliminated, and only magnetic toroid-like modes are sustainable in the infrared and visible regime. All of these deep-subwavelength modes can be interpreted as an interference effect from the gap surface plasmon polaritons. Our results will be useful in nanoantenna design, high-Q cavity sensing, structured light-beam generation, and photon e...

  16. CLUSTER: A high-frequency H-mode coupled cavity linac for low and medium energies

    Energy Technology Data Exchange (ETDEWEB)

    Amaldi, Ugo [TERA Foundation, Via Puccini 11, 28100 Novara (Italy); University of Milano Bicocca, Milan (Italy)], E-mail: Ugo.Amaldi@cern.ch; Citterio, Alessandro; Crescenti, Massimo; Giuliacci, Arianna; Tronci, Cesare; Zennaro, Riccardo [TERA Foundation, Via Puccini 11, 28100 Novara (Italy)

    2007-09-11

    An innovative linear accelerating structure is proposed which is particularly suited for low-current hadrontherapy applications but can also conveniently substitute the conventional proton linacs at present considered for Accelerator Driven Systems and neutrino and muon factories. Its two main features are compactness and good power efficiency at low-medium beam velocities (0.05{<=}{beta}{<=}0.5). The first is achieved through a high working frequency and a consequent high accelerating gradient, the second is obtained by coupling several H-mode cavities together. The structure was dubbed CLUSTER for 'Coupled-cavity Linac USing Transverse Electric Radial field'. To compare the performance of this structure with other hadrontherapy linac designs involving high frequencies, a conceptual study has been performed for an operating frequency of 3 GHz. Moreover, a proof of principle has been obtained through RF measurements on a prototype operating at 1 GHz. An accelerator complex using a CLUSTER linac is also considered for protontherapy purposes. This total accelerator complex, called 'cyclinac', uses a commercial cyclotron as an injector to a high-frequency and high-gradient linac.

  17. Analysis and engineering of coupled cavity waveguides based on coupled-mode theory

    Institute of Scientific and Technical Information of China (English)

    Lin Xu-Sheng; Chen Xiong-Wen; Lan Sheng

    2005-01-01

    The analytical expression for the transmission spectra of coupled cavity waveguides (CCWs) in photonic crystals (PCs) is derived based on the coupled-mode theory (CMT). Parameters in the analytical expression can be extracted by simple numerical simulations. We reveal that it is the phase shift between the two adjacent PC defects that uniquely determines the flatness of the impurity bands of CCWs. In addition, it is found that the phase shift also greatly affects the bandwidth of CCWs. Thus, the engineering of the impurity bands of CCWs can be realized through the adjustment of the phase shift. Based on the theoretical results, an interesting phenomenon in which a CCW acts as a single PC defect and its impurity band possesses a Lorentz lineshape is predicted. Very good agreement between the analytical results and the numerical simulations based on transfer matrix method has been achieved.

  18. Cavity QED quantum phase gates for a single longitudinal mode of the intracavity field

    CERN Document Server

    García-Maraver, R; Eckert, K; Rebic, S; Artoni, M; Mompart, J

    2004-01-01

    A single three-level atom driven by a longitudinal mode of a high-Q cavity is used to implement two-qubit quantum phase gates for the intracavity field. The two qubits are associated to the zero-and one-photon Fock states of each of the two opposite circular polarization states of the field. The three-level atom yields the conditional phase gate provided the two polarization states and the atom interact in a $V$-type configuration and the two photon resonance condition is fulfilled. Microwave and optical implementations are discussed with gate fidelities being evaluated against several decoherence mechanisms such as atomic velocity fluctuations or the presence of a weak magnetic field. The use of coherent states for both polarization states is investigated to assess the entanglement capability of the proposed quantum gates.

  19. Superspace Cavity QED Blackbody Equilibrium Modes Delineating CMBR Emission and Non-Doppler Redshift Absorption

    Science.gov (United States)

    Amoroso, Richard

    2004-05-01

    A blackbody equilibrium cavity QED theory for CMBR as emission and non-Doppler redshift as absorption is formulated utilizing an advanced form of Einstein's steady state cosmology. This Continuous State Universe (CSU) is based on a highly ordered periodic superspace that includes an energy dependent spacetime metric. The formalism for the superspace is derived by extending the Wheeler-Feynman absorber theory of radiation to the topology of the 12D periodic superspace. A fundamental least unit contains a core of Dirac spherical rotation with an inherent continuous compactification and dimensional reduction. It is shown formally that parameters of this cosmology demonstrate blackbody equilibrium conditions compatible with modes of emission and absorption suitable for describing CMBR and non-Doppler redshift.

  20. Wirebond crosstalk and cavity modes in large chip mounts for superconducting qubits

    Energy Technology Data Exchange (ETDEWEB)

    Wenner, J; Neeley, M; Bialczak, Radoslaw C; Lenander, M; Lucero, Erik; O' Connell, A D; Sank, D; Wang, H; Weides, M; Cleland, A N; Martinis, John M, E-mail: martinis@physics.ucsb.edu [Department of Physics, University of California, Santa Barbara, CA 93106 (United States)

    2011-06-15

    We analyze the performance of a microwave chip mount that uses wirebonds to connect the chip and mount grounds. A simple impedance ladder model predicts that transmission crosstalk between two feedlines falls off exponentially with distance at low frequencies, but rises to near unity above a resonance frequency set by the chip to ground capacitance. Using SPICE simulations and experimental measurements of a scale model, the basic predictions of the ladder model were verified. In particular, by decreasing the capacitance between the chip and box grounds, the resonance frequency increased and transmission decreased. This model then influenced the design of a new mount that improved the isolation to - 65 dB at 6 GHz, even though the chip dimensions were increased to 1 cm x 1 cm, three times as large as our previous devices. We measured a coplanar resonator in this mount as preparation for larger qubit chips, and were able to identify cavity, slotline, and resonator modes.

  1. Cavity QED quantum phase gates for a single longitudinal mode of the intracavity field

    Science.gov (United States)

    García-Maraver, R.; Corbalán, R.; Eckert, K.; Rebić, S.; Artoni, M.; Mompart, J.

    2004-12-01

    A single three-level atom driven by a longitudinal mode of a high- Q cavity is used to implement two-qubit quantum phase gates for the intracavity field. The two qubits are associated with the zero- and one-photon Fock states of each of the two opposite circular polarization states of the field. The three-level atom mediates the conditional phase gate provided the two polarization states and the atom interact in a V-type configuration and the two-photon resonance condition is satisfied. Microwave and optical implementations are discussed with gate fidelities being evaluated against several decoherence mechanisms such as atomic velocity fluctuations or the presence of a weak magnetic field. The use of coherent states for both polarization states is investigated to assess the entanglement capability of the proposed quantum gates.

  2. Reply to "Comment on `Normalization of quasinormal modes in leaky optical cavities and plasmonic resonators' "

    Science.gov (United States)

    Kristensen, Philip Trøst; Ge, Rong-Chun; Hughes, Stephen

    2017-07-01

    We refute all claims of the "Comment on `Normalization of quasinormal modes in leaky optical cavities and plasmonic resonators' " by E. A. Muljarov and W. Langbein. Based entirely on information already contained in our original article [P. T. Kristensen, R.-C. Ge, and S. Hughes, Phys. Rev. A 92, 053810 (2015), 10.1103/PhysRevA.92.053810], we dismiss every point of criticism as being unsupported and point out how important parts of our argumentation appear to have been overlooked by the Comment authors. In addition, we provide additional calculations showing directly the connection between the normalizations by Sauvan et al. and Muljarov et al., which were not included in our original article.

  3. Time-delay signatures in multi-transverse mode VCSELs subject to double-cavity polarization-rotated optical feedback

    Science.gov (United States)

    Lin, Hong; Khurram, Aliza; Hong, Yanhua

    2016-10-01

    Time delay (TD) signatures are studied experimentally in orthogonal polarizations and in individual transverse modes respectively in a VCSEL operating with three transverse modes. Different types of concealment of the TD signatures are observed when the polarization of feedback is rotated through large angles. Effects of feedback strength and external cavity length on the TD signatures are investigated. Weak feedback leads to better concealment of the TD signatures in the dominant polarization. When the round-trip time difference between the two external cavities is close to a half of the relaxation oscillation period, the TD signatures are minimized.

  4. Single mode operation and extended scanning of anti-reflection coated visible laser diodes in a Littrow cavity

    Science.gov (United States)

    Lonsdale, D. J.; Andrews, D. A.; King, T. A.

    2004-05-01

    A method to increase the mode-hop-free tuning range is presented that is suitable for application with visible and short wavelength laser diodes, and relaxes the requirement on high tolerance mechanical components. Depending on the diode and cavity, the theory predicts an improvement of up to eight times the FSR of the extended cavity. In our system, an anti-reflection coated AlGaInP laser diode showed a mode-hop-free scan of 8 GHz, which is characteristic for the wavelength used in the device. Greater scanning ranges are predicted for shorter wavelength sources.

  5. Effect of irradiation mode and filling technique on resin/dentin bonding strength in Class I cavities.

    Science.gov (United States)

    dos Santos, Alex José Souza; Giannini, Marcelo; Paulillo, Luis Alexandre Maffei Sartini; Lovadino, José Roberto; de Carvalho, Ricardo Marins

    2004-01-01

    Factors such as light-curing mode, filling technique and cavity configuration may affect the bonding strength to dentin. This study evaluated the effect of irradiation mode and filling technique on resin/dentin bonding strength on the buccal wall of Class I cavities in human teeth. Occlusal enamel was removed to expose a flat dentin surface. Occlusal cavities (4 x 3 x 3 mm) were prepared in dentin. The adhesive Single Bond was applied according to the manufacturer's instructions and TPH Spectrum composite resin was placed using the following: oblique incremental, horizontal incremental or bulk filling techniques. The composite resin was light-cured either by continuous (600 mW/cm2 for 40 s) or Soft-Start (250 mW/cm2 for 10 s + 600 mW/cm2 for 30 s) modes. Specimens of the control group were obtained by bonding the material to the flat exposed buccal wall of the cavity (C-factor = 1). The teeth were stored in water at 37 degrees C for 24 h and prepared for microtensile testing. Bonded beams of approximately 0.8 mm2 were obtained from the buccal wall and tested with a tension of 0.5 mm/min. Results were analyzed by two-way ANOVA, Tukey's test and Dunnett's test (alpha = 0.05). Incremental placement techniques with both irradiation modes produced higher bonding strength values than the bulk technique (p < 0.05). Bonding strength tested in the cavities had lower values than those obtained in flat dentin surfaces (control group) (p < 0.05), except for incremental fillings using stepped irradiation. Bonding strength to the cavity walls depends on the filling technique and on the irradiation mode of composite resins.

  6. Status of Higher Order Mode Beam Position Monitors in 3.9 GHz Superconducting Accelerating Cavities at FLASH

    CERN Document Server

    Zhang, P; Flisgen, T; van Rienen, U; Jones, R M; Shinton, I R R

    2013-01-01

    Higher order mode (HOM) beam position monitors (BPM) are being developed for the 3.9 GHz third harmonic superconducting accelerating cavities at FLASH. The transverse beam position in a cavity can be determined utilizing beam-excited HOMs based on dipole components. The existing couplers used for HOM suppression provide necessary signals. The diagnostics principle is similar to a cavity BPM, but requires no additional vacuum instruments on the linac. The challenges of HOM-BPM for 3.9 GHz cavities lie in the dense HOM spectrum arising from the coupling of the majority HOMs amongst the four cavities in the cryo-module ACC39. HOMs with particularly promising diagnostics features were evaluated using a spectrum analyzer and custom-built test electronics with various data analysis techniques, data reduction was focused on. After careful theoretical and experimental assessment of the HOM spectrum, multi-cavity modes in the region of 5 GHz were chosen to provide a global position over the complete module with superi...

  7. Status of higher order mode beam position monitors in 3.9 GHz superconducting accelerating cavities at FLASH

    CERN Document Server

    Zhang, P; Jones, R M; Flisgen, T; Van Rienen, U; Shinton, I R R

    2013-01-01

    Higher order mode (HOM) beam position monitors (BPM) are being developed for the 3.9 GHz third harmonic superconducting accelerating cavities at FLASH. The transverse beam position in a cavity can be determined utilizing beam-excited HOMs based on dipole components. The existing couplers used for HOM suppression provide necessary signals. The diagnostics principle is similar to a cavity BPM, but requires no additional vacuum instruments on the linac. The challenges of HOM-BPM for 3.9 GHz cavities lie in the dense HOM spectrum arising from the coupling of the majority HOMs amongst the four cavities in the cryo-module ACC39. HOMs with particularly promising diagnostics features were evaluated using a spectrum analyzer and custom-built test electronics with various data analysis techniques, data reduction was focused on. After careful theoretical and experimental assessment of the HOM spectrum, multi-cavity modes in the region of 5 GHz were chosen to provide a global position over the complete module with superi...

  8. Higher-order Laguerre-Gauss modes in (non-) planar four-mirror cavities for future gravitational wave detectors.

    Science.gov (United States)

    Noack, Andreas; Bogan, Christina; Willke, Benno

    2017-02-15

    One of the limiting noise sources in the current generation of gravitational wave detectors, such as the advanced laser interferometer gravitational wave observatory (aLIGO), is the thermal noise in the interferometer's test mass coatings. One proposed method to reduce the coupling of this noise source to the gravitational wave readout is using a laser beam in the higher-order spatial LG33 mode within the interferometer. Here we show that the current four-mirror cavities of aLIGO are not compatible with Laguerre-Gauss modes due to astigmatism. A non-degeneracy of modes of the same order could be observed in experiment and simulation. We demonstrate that a non-planar cavity could be used instead as it compensates for the astigmatism and transmits the LG33 mode undisturbed.

  9. Coexistence of Scattering Enhancement and Suppression by Plasmonic Cavity Modes in Loaded Dimer Gap-Antennas.

    Science.gov (United States)

    Zhang, Qiang; Xiao, Jun-Jun; Li, Meili; Han, Dezhuan; Gao, Lei

    2015-11-27

    Plasmonic nanoantenna is of promising applications in optical sensing and detection, enhancement of optical nonlinear effect, surface optical spectroscopy, photoemission, etc. Here we show that in a carefully-designed dimer gap-antenna made by two metallic nanorods, the longitudinal plasmon antenna mode (AM) of bonding dipoles can compete with the transverse plasmonic cavity modes (CMs), yielding dramatically enhanced or suppressed scattering efficiency, depending on the CMs symmetry characteristics. More specifically, it is demonstrated that an appropriately loaded gap layer enables substantial excitation of toroidal moment and its strong interaction with the AM dipole moment, resulting in Fano- or electromagnetically induced transparency (EIT)-like profile in the scattering spectrum. However, for CMs with nonzero azimuthal number, the spectrum features a cumulative signature of the respective AM and CM resonances. We supply both detailed near-field and far-field analysis, showing that the modal overlap and phase relationship between the fundamental moments of different order play a crucial role. Finally, we show that the resonance bands of the AM and CMs can be tuned by adjusting the geometry parameters and the permittivity of the load. Our results may be useful in plasmonic cloaking, spin-polarized directional light emission, ultra-sensitive optical sensing, and plasmon-mediated photoluminescence.

  10. Towards monolithic integration of mode-locked vertical cavity surface emitting laser

    Science.gov (United States)

    Aldaz, Rafael I.

    2007-12-01

    The speed and performance of today's high end computing and communications systems have placed difficult but still feasible demands on off-chip electrical interconnects. However, future interconnect systems may need aggregate bandwidths well into the terahertz range thereby making electrical bandwidth, density, and power targets impossible to meet. Optical interconnects, and specifically compact semiconductor mode-locked lasers, could alleviate this problem by providing short pulses in time at 10s of GHz repetition rates for Optical Time Division Multiplexing (OTDM) and clock distribution applications. Furthermore, the characteristic spectral comb of frequencies of these lasers could also serve as a multi-wavelength source for Wavelength Division Multiplexing (WDM) applications. A fully integrated mode-locked Vertical Cavity Surface Emitting Laser (VCSEL) is proposed as a low-cost high-speed source for these applications. The fundamental laser platform for such a device has been developed and a continuous-wave version of these lasers has been fabricated and demonstrated excellent results. Output powers close to 60mW have been obtained with very high beam quality factor of M2 unassisted ultrafast QD saturable absorbers, without the need to incorporate high concentrations of non radiative recombination centers by either ion-implantation or low temperature growth.

  11. Multipartite entanglement in the interaction system between a single-mode microwave cavity field and superconducting charge qubits

    Institute of Scientific and Technical Information of China (English)

    Shi Zhen-Gang; Chen Xiong-Wen; Zhu Xi-Xiang; Song Ke-Hui

    2007-01-01

    This paper proposes a method of generating multipartite entanglement through using d. c. superconducting quantum interference devices (SQUID) inside a standing wave cavity. In this scheme, the d. c. SQUID works in the charge region. It is shown that, a large number of important multipartite entangled states can be generated by a controllable interaction between a cavity field and qubits. It is even possible to produce entangled states involving different cavity modes based on the measurement of charge qubits states. After such superpositions states are created, the interaction can be switched off by the classical magnetic field through the SQUID, and there is no information transfer between the cavity field and the charge qubits.

  12. Semianalytical quasi-normal mode theory for the local density of states in coupled photonic crystal cavity-waveguide structures.

    Science.gov (United States)

    de Lasson, Jakob Rosenkrantz; Kristensen, Philip Trøst; Mørk, Jesper; Gregersen, Niels

    2015-12-15

    We present and validate a semianalytical quasi-normal mode (QNM) theory for the local density of states (LDOS) in coupled photonic crystal (PhC) cavity-waveguide structures. By means of an expansion of the Green's function on one or a few QNMs, a closed-form expression for the LDOS is obtained, and for two types of two-dimensional PhCs, with one and two cavities side-coupled to an extended waveguide, the theory is validated against numerically exact computations. For the single cavity, a slightly asymmetric spectrum is found, which the QNM theory reproduces, and for two cavities, a nontrivial spectrum with a peak and a dip is found, which is reproduced only when including both the two relevant QNMs in the theory. In both cases, we find relative errors below 1% in the bandwidth of interest.

  13. The Influence of Tuners and Temperature on the Higher Order Mode Spectrum for 1.3 GHz SCRF Cavities

    CERN Document Server

    Ainsworth, R; Zhang, P; Grecki, M; Baboi, N; Wamsat, T; Eddy, N

    2013-01-01

    Higher Order Modes (HOMs) are of concern for superconducting cavities as they can drive instabilities and so are usually damped and monitored. With special dedicated electronics, HOMs can provide information on the position on the beam. It has been proposed that piezo tuners used to keep the cavities operating at 1.3 GHz could alter the HOM spectrum altering the calibration constants used to read out the beam position affecting long term stability of the system. Also, of interest is how the cavity reacts to the slow tuner. Detuning and the retuning the cavity may alter the HOM spectrum. This is of particular interest for future machines not planning to use dedicated HOM damping as the tuning procedure may shift the frequency of HOMs onto dangerous resonances. The effect of temperature on the HOM spectrum is also investigated. An investigation of these effects has been performed at FLASH and the results are presented.

  14. Optomechanical coupling between two optical cavities: cooling of a micro-mirror and parametric normal mode splitting

    CERN Document Server

    Kumar, Tarun; ManMohan,

    2011-01-01

    We propose a technique aimed at cooling a harmonically oscillating mirror mechanically coupled to another vibrating mirror to its quantum mechanical ground state. Our method involves optmechanical coupling between two optical cavities. We show that the cooling can be controlled by the mechanical coupling strength between the two movable mirrors, the phase difference between the mechanical modes of the two oscillating mirrors and the photon number in each cavity. We also show that both mechanical and optical cooling can be achieved by transferring energy from one cavity to the other. We also analyze the occurrence of normal-mode splitting (NMS). We find that a hybridization of the two oscillating mirrors with the fluctuations of the two driving optical fields occurs and leads to a splitting of the mechanical and optical fluctuation spectra.

  15. Crab Cavity Development

    CERN Document Server

    Calaga, R; Burt, G; Ratti, A

    2015-01-01

    The HL-LHC upgrade will use deflecting (or crab) cavities to compensate for geometric luminosity loss at low β* and non-zero crossing angle. A local scheme with crab cavity pairs across the IPs is used employing compact crab cavities at 400 MHz. Design of the cavities, the cryomodules and the RF system is well advanced. The LHC crab cavities will be validated initially with proton beam in the SPS.

  16. Cavity mode waves during terahertz radiation from rectangular Bi(2)Sr(2)CaCu(2)O(8 + δ) mesas.

    Science.gov (United States)

    Klemm, Richard A; Laberge, Erica R; Morley, Dustin R; Kashiwagi, Takanari; Tsujimoto, Manabu; Kadowaki, Kazuo

    2011-01-19

    We re-examined the angular dependence of the radiation from the intrinsic Josephson junctions in rectangular mesas of Bi(2)Sr(2)CaCu(2)O(8 + δ), in order to determine if the cavity mode part of the radiation arises from waves across the width w or along the length l of the mesas, associated with 'hot spots' (Wang et al 2010 Phys. Rev. Lett. 105 057002). We derived analytical forms for the angular dependence expected in both cases for a general cavity mode in which the width of the mesa corresponds to an integer multiple of one-half the wavelength of the radiation. Assuming the coherent radiation from the ac Josephson current source and the cavity magnetic surface current density source combine incoherently, fits to the data of Kadowaki et al (2010 J. Phys. Soc. Japan 79 023703) on a mesa with mean l/ω = 5.17 for both wave directions using two models for the incoherent combination were made, which correspond to standing and traveling waves, respectively. The results suggest that the combined output from the uniform ac Josephson current source plus a cavity wave forming along the rectangle length is equally probable as that of the combined output from the uniform ac Josephson current plus a cavity wave across the width. However, for mesas in which nl/2ω is integral, where n is the index of the rectangular TM(z)(n, 0) mode, it is shown that standing cavity mode waves along the length of the mesa do not radiate in the xz plane perpendicular to the length of the mesa, suggesting experiments on such mesas could help to resolve the question.

  17. Cavity mode waves during terahertz radiation from rectangular Bi2Sr2CaCu2O8 + δ mesas

    Science.gov (United States)

    Klemm, Richard A.; LaBerge, Erica R.; Morley, Dustin R.; Kashiwagi, Takanari; Tsujimoto, Manabu; Kadowaki, Kazuo

    2011-01-01

    We re-examined the angular dependence of the radiation from the intrinsic Josephson junctions in rectangular mesas of Bi2Sr2CaCu2O8 + δ, in order to determine if the cavity mode part of the radiation arises from waves across the width w or along the length \\ell of the mesas, associated with 'hot spots' (Wang et al 2010 Phys. Rev. Lett. 105 057002). We derived analytical forms for the angular dependence expected in both cases for a general cavity mode in which the width of the mesa corresponds to an integer multiple of one-half the wavelength of the radiation. Assuming the coherent radiation from the ac Josephson current source and the cavity magnetic surface current density source combine incoherently, fits to the data of Kadowaki et al (2010 J. Phys. Soc. Japan 79 023703) on a mesa with mean \\ell /w=5.17 for both wave directions using two models for the incoherent combination were made, which correspond to standing and traveling waves, respectively. The results suggest that the combined output from the uniform ac Josephson current source plus a cavity wave forming along the rectangle length is equally probable as that of the combined output from the uniform ac Josephson current plus a cavity wave across the width. However, for mesas in which n\\ell /2w is integral, where n is the index of the rectangular TMzn, 0 mode, it is shown that standing cavity mode waves along the length of the mesa do not radiate in the xz plane perpendicular to the length of the mesa, suggesting experiments on such mesas could help to resolve the question.

  18. Multiple harmonic frequencies resonant cavity design and half-scale prototype measurements for a fast kicker

    Science.gov (United States)

    Huang, Yulu; Wang, Haipeng; Rimmer, Robert A.; Wang, Shaoheng; Guo, Jiquan

    2016-12-01

    Quarter wavelength resonator (QWR) based deflecting cavities with the capability of supporting multiple odd-harmonic modes have been developed for an ultrafast periodic kicker system in the proposed Jefferson Lab Electron Ion Collider (JLEIC, formerly MEIC). Previous work on the kicking pulse synthesis and the transverse beam dynamics tracking simulations show that a flat-top kicking pulse can be generated with minimal emittance growth during injection and circulation of the cooling electron bunches. This flat-top kicking pulse can be obtained when a DC component and 10 harmonic modes with appropriate amplitude and phase are combined together. To support 10 such harmonic modes, four QWR cavities are used with 5, 3, 1, and 1 modes, respectively. In the multiple-mode cavities, several slightly tapered segments of the inner conductor are introduced to tune the higher order deflecting modes to be harmonic, and stub tuners are used to fine tune each frequency to compensate for potential errors. In this paper, we summarize the electromagnetic design of the five-mode cavity, including the geometry optimization to get high transverse shunt impedance, the frequency tuning and sensitivity analysis, and the single loop coupler design for coupling to all of the harmonic modes. In particular we report on the design and fabrication of a half-scale copper prototype of this proof-of-principle five-odd-mode cavity, as well as the rf bench measurements. Finally, we demonstrate mode superposition in this cavity experimentally, which illustrates the kicking pulse generation concept.

  19. Multiple-bunch-length operating mode design for a storage ring using hybrid low alpha and harmonic cavity method

    Science.gov (United States)

    Gao, Weiwei; Wang, Lin; Li, Heting

    2017-03-01

    In this paper we design a simultaneous three bunch length operating mode at the HLS-II (Hefei Light Source II) storage ring by installing two harmonic cavities and minimizing the momentum compaction factor. The short bunches (2.6 mm) presented in this work will meet the requirement of coherent millimeter-wave and sub-THz radiation experiments, while the long bunches (20 mm) will efficiently increase the total beam current. Therefore, this multiple-bunch-length operating mode allows present synchrotron users and coherent millimeter-wave users (or sub THz users) to carry out their experiments simultaneously. Since the relatively low energy characteristic of HLS-II we achieve the multiple-bunch-length operating mode without multicell superconducting RF cavities, which is technically feasible.

  20. Noninvasive Vibrational Mode Spectroscopy of Ion Coulomb Crystals through Resonant Collective Coupling to an Optical Cavity Field

    DEFF Research Database (Denmark)

    Dantan, Aurélien; Marler, Joan; Albert, Magnus

    2010-01-01

    We report on a novel noninvasive method to determine the normal mode frequencies of ion Coulomb crystals in traps based on the resonance enhanced collective coupling between the electronic states of the ions and an optical cavity field at the single photon level. Excitations of the normal modes...... are observed through a Doppler broadening of the resonance. An excellent agreement with the predictions of a zero-temperature uniformly charged liquid plasma model is found. The technique opens up for investigations of the heating and damping of cold plasma modes, as well as the coupling between them....

  1. High-Power Hybrid Mode-Locked External Cavity Semiconductor Laser Using Tapered Amplifier with Large Tunability

    Directory of Open Access Journals (Sweden)

    Andreas Schmitt-Sody

    2008-01-01

    Full Text Available We report on hybrid mode-locked laser operation of a tapered semiconductor amplifier in an external ring cavity, generating pulses as short as 0.5 ps at 88.1 MHz with an average power of 60 mW. The mode locking is achieved through a combination of a multiple quantum well saturable absorber (>10% modulation depth and an RF current modulation. This designed laser has 20 nm tuning bandwidth in continuous wave and 10 nm tuning bandwidth in mode locking around 786 nm center wavelength at constant temperature.

  2. Design and Applications of In-Cavity Pulse Shaping by Spectral Sculpturing in Mode-Locked Fibre Lasers

    Directory of Open Access Journals (Sweden)

    Sonia Boscolo

    2015-11-01

    Full Text Available We review our recent progress on the realisation of pulse shaping in passively-mode-locked fibre lasers by inclusion of an amplitude and/or phase spectral filter into the laser cavity. We numerically show that depending on the amplitude transfer function of the in-cavity filter, various regimes of advanced waveform generation can be achieved, including ones featuring parabolic-, flat-top- and triangular-profiled pulses. An application of this approach using a flat-top spectral filter is shown to achieve the direct generation of high-quality sinc-shaped optical Nyquist pulses with a widely tunable bandwidth from the laser oscillator. We also present the operation of an ultrafast fibre laser in which conventional soliton, dispersion-managed soliton (stretched-pulse and dissipative soliton mode-locking regimes can be selectively and reliably targeted by adaptively changing the dispersion profile and bandwidth programmed on an in-cavity programmable filter. The results demonstrate the strong potential of an in-cavity spectral pulse shaper for achieving a high degree of control over the dynamics and output of mode-locked fibre lasers.

  3. Terahertz plasmon-polariton modes in graphene driven by electric field inside a Fabry-Pérot cavity

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, C. X.; Li, L. L.; Zhang, C. [Key Laboratory of Materials Physics, Institute of Solid State Physics, Chinese Academy of Sciences, Hefei 230031 (China); Xu, W., E-mail: wenxu-issp@aliyun.com [Key Laboratory of Materials Physics, Institute of Solid State Physics, Chinese Academy of Sciences, Hefei 230031 (China); Department of Physics, Yunnan University, Kunming 650091 (China); Peeters, F. M. [Department of Physics, University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerpen (Belgium)

    2015-06-14

    We present a theoretical study on plasmon-polariton modes in graphene placed inside an optical cavity and driven by a source-to-drain electric field. The electron velocity and electron temperature are determined by solving self-consistently the momentum- and energy-balance equations in which electron interactions with impurities, acoustic-, and optic-phonons are included. Based on many-body self-consistent field theory, we develop a tractable approach to study plasmon-polariton in an electron gas system. We find that when graphene is placed inside a Fabry-Pérot cavity, two branches of the plasmon-polariton modes can be observed and these modes are very much optic- or plasmon-like. The frequencies of these modes depend markedly on driving electric field especially at higher resonant frequency regime. Moreover, the plasmon-polariton frequency in graphene is in terahertz (THz) bandwidth and can be tuned by changing the cavity length, gate voltage, and driving electric field. This work is pertinent to the application of graphene-based structures as tunable THz plasmonic devices.

  4. Theoretical and experimental investigation of the mode-spacing of fiber Bragg grating Fabry-Perot cavity

    Institute of Scientific and Technical Information of China (English)

    Wenhua Ren; Peilin Tao; Zhongwei Tan; Yan Liu; Shuisheng Jian

    2009-01-01

    The mode-spacing of the fiber Bragg grating Fabry-Perot(FBG F-P)cavity is calculated by using the effective cavity length which contains the effective length of the FBG.The expression of the effective length,defined by using the phase-time delay,is obtained and simplified as a function of the peak reflectivity at the Bragg wavelength,the band edges,and the first zero-reflectivity wavelength.The effective length is discussed from the energy penetration depth point of view.Three FBG F-P cavities are fabricated in order to validate the effective length approach.The experimental data fits well with the theoretical predictions.The limitation of this method is also pointed out and the improved approach is proposed.

  5. Wakefield calculation for superconducting TM110 cavity without azimuthal symmetry

    Energy Technology Data Exchange (ETDEWEB)

    Bellantoni, Leo; /Fermilab; Burt, Graeme; /Lancaster U.

    2006-08-01

    The 3.9GHz TM{sub 110} mode deflecting cavity developed at FNAL has many applications, including use as a longitudinal bunch profile diagnostic, and as a crab cavity candidate for the ILC. These applications involve beams with substantial time structure. For the 13-cell version intended for the bunch profile application, long-range wakes have been evaluated in the frequency domain and short-range wakes have been evaluated in the time domain. Higher-order interactions of the main field in the cavity with the beam have also been parameterized. Pedagogic derivations are included as appendices.

  6. Passively Q-switched Single-longitudinal-mode c-cut Nd:GdVO4 laser with a twisted-mode cavity.

    Science.gov (United States)

    Pan, Haifeng; Xu, Shixiang; Zeng, Heping

    2005-04-04

    Single-longitudinal-mode operation is achieved in a twisted-mode-cavity c-cut Nd:GdVO4 laser. With a semiconductor saturable absorption mirror as an intracavity saturable absorber to launch passive Q-switching, no mode-locked spikes are observed on the temporal envelopes of the Q-switched output pulses due to the complete elimination of spatial hole burning in the gain medium to suppress longitudinal multi-modes. The maximal average output power is 1.24 W with the repetition rate of 76.3 kHz, and the single pulse energy is 16.0 microJ. The pulse width and polarization ratio of the output laser beam are measured about 150 ns and 53:1, respectively.

  7. Quantitative coupled-mode model for a metal-dielectric-metal waveguide with a side-coupled cavity.

    Science.gov (United States)

    Zhong, Ying; Zhou, Hongkun; Liu, Haitao

    2014-10-01

    The Fabry-Perot model is proposed to analyze the wavelength-selective transmission behaviors of the metal-dielectric-metal waveguide with a rectangular side-coupled cavity. The guided modes propagating in the waveguide and the cavity are extracted by the aperiodic Fourier modal method (a-FMM). The scattering coefficients that appeared in the model are calculated by the a-FMM and the normal-mode theory. The applications of such structure in the wavelength-selective filter and the refractive index sensor are also discussed. Our model is shown to accurately predict the fully vectorial data and thus can provide reliable and quantitative analysis of this kind of device.

  8. Engineering of a Superconducting 400 MHz Crabbing Cavity for the LHC HiLumi Upgrade

    CERN Document Server

    Gorelov, D; De Silva, S U; Delayen, Jean Roger

    2012-01-01

    The recently developed new simplified design for the 400 MHz LHC crabbing cavity presents attractive properties compared to conventional designs. The proposed approach can be equally compact in both transverse dimensions and allows horizontal as well as vertical deflection of the beam in the collider. The significant modification of the parallel-bar design with the bars merged to the side walls of the cavity gives improved properties, such as better mode separation and reduced surface fields*. A transverse deflecting voltage of 3 to 5 MV in a single cavity can be expected with the peak surface electric field lower then 50 MV/m and peak magnetic field below 100 mT. This paper presents engineering issues of the proof-of-concept crabbing cavity d esign and discusses the manufacturing techniques. The paper discusses present status of the project including fabrication of the niobium cavity, as well as room temperature and cryogenic testing.

  9. Design of Electron and Ion Crabbing Cavities for an Electron-Ion Collider

    Energy Technology Data Exchange (ETDEWEB)

    Alejandro Castilla Loeza, Geoffrey Krafft, Jean Delayen

    2012-07-01

    Beyond the 12 GeV upgrade at the Jefferson Lab a Medium Energy Electron-Ion Collider (MEIC) has been considered. In order to achieve the desired high luminosities at the Interaction Points (IP), the use of crabbing cavities is under study. In this work, we will present to-date designs of superconducting cavities, considered for crabbing both ion and electron bunches. A discussion of properties such as peak surface fields and higher-order mode separation will be presented. Keywords: super conducting, deflecting cavity, crab cavity.

  10. Modeling of tuning of microresonator filters by perturbational evaluation of cavity mode phase shifts

    NARCIS (Netherlands)

    Hiremath, K.R.; Lohmeyer, Manfred

    2007-01-01

    Microresonator filters, realized by evanescent coupling of circular cavities with two parallel bus waveguides, are promising candidates for applications in dense wavelength division multiplexing. Tunability of these filters is an essential feature for their successful deployment. In this paper we

  11. Microplasma mode transition and corresponding propagation characteristics controlled by manipulating electric field strength in a microchannel-cavity hybrid structure device

    Science.gov (United States)

    Wang, Y.; Ni, J. H.; Zhong, S.; Zhang, X.; Liang, Z.; Liu, C.; Park, S.-J.; Eden, J. G.

    2016-10-01

    Plasma redistribution in a symmetric microchannel-cavity hybrid structure device has been investigated by modulating the applied electric field strength. The device array has been operated in 200 Torr of argon, driven by a 20 kHz bipolar waveform. With the existence of the intervening microchannel between microcavities, several stable modes of operation of the microplasma have been observed, including cavity mode, hybrid mode and channel mode. Transition between the modes occurs with modulation of the applied voltage from 800 to 1100 V. The characteristics of microplasma propagation in different modes are investigated and the propagation speed along diagonal direction of the device in cavity mode, hybrid and channel mode are calculated to be ~48, ~29 and ~32 km s-1, respectively. Nonhomogeneous electric field strength distribution and plasma interaction have been discussed to explain these experimental results. Emission intensity and propagation speed differences in the cavity mode between the polarities of the applied voltage are interpreted through spatially resolved measurements of the emission profile in a partial channel-cavity array.

  12. Base deflection and microleakage of composite restorations.

    Science.gov (United States)

    Paulillo, L A; de Goes, M F; Consani, S

    1994-06-01

    The flexural deflections of human dentin, Herculite XR, Dycal, Vidrion F, zinc phosphate base, and combinations of composite-base were determined. The influence of the flexural deflections in the marginal microleakage was also determined for the composite-base combinations. The flexural deflection test for dentin showed no statistically significant differences between the two floor cavity depths studied. There were significant differences among cements when the thickness of the base was 1 mm whereas no differences occurred at 2 mm. The composite-base combinations did not present statistical differences. There were no statistically significant differences in the microleakage levels among loaded and non-loaded specimens; however, dye penetration was visually greater in loaded samples.

  13. Stable single longitudinal mode erbium-doped silica fiber laser based on an asymmetric linear three-cavity structure

    Institute of Scientific and Technical Information of China (English)

    Feng Ting; Yan Feng-Ping; Li Qi; Peng Wan-Jing; Feng Su-Chun; Tan Si-Yu; Wen Xiao-Dong

    2013-01-01

    We present a stable linear-cavity single longitudinal mode (SLM) erbium-doped silica fiber laser.It consists of four fiber Bragg gratings (FBGs) directly written in a section of photosensitive erbium-doped fiber (EDF) to form an asymmetric three-cavity structure.The stable SLM operation at a wavelength of 1545.112 nm with a 3-dB bandwidth of 0.012 nm and an optical signal-to-noise ratio (OSNR) of about 60 dB is verified experimentally.Under laboratory conditions,the performance of a power fluctuation of less than 0.05 dB observed from the power meter for 6 h and a wavelength variation of less than 0.01 nm obtained from the optical spectrum analyzer (OSA) for about 1.5 h are demonstrated.The gain fiber length is no longer limited to only several centimeters for SLM operation because of the excellent mode-selecting ability of the asymmetric three-cavity structure.The proposed scheme provides a simple and cost-effective approach to realizing a stable SLM fiber laser.

  14. Tunable waveguide and cavity in a phononic crystal plate by controlling whispering-gallery modes in hollow pillars

    DEFF Research Database (Denmark)

    Jin, Yabin; Fernez, Nicolas; Pennec, Yan;

    2016-01-01

    We investigate the properties of a phononic crystal plate with hollow pillars and introduce the existence of whispering-gallery modes (WGMs). We show that by tuning the inner radius of the hollow pillar, these modes can merge inside both Bragg and low frequency band gaps, deserving phononic crystal...... and acoustic metamaterial applications. These modes can be used as narrow pass bands for which the quality factor can be greatly enhanced by the introduction of an additional cylinder between the hollow cylinder and the plate. We discuss some functionalities of these confined WGM in both Bragg and low...... frequency gaps for wavelength division in multiplexer devices using heteroradii pillars introduced into waveguide and cavity structures....

  15. Strong optomechanical coupling in a slotted photonic crystal nanobeam cavity with an ultrahigh quality factor-to-mode volume ratio

    CERN Document Server

    Schneider, Katharina

    2016-01-01

    We describe the design, fabrication, and characterization of a one-dimensional silicon photonic crystal cavity in which a central slot is used to enhance the overlap between highly localized optical and mechanical modes. The optical mode has an extremely small mode volume of 0.017 $(\\lambda_{vac}/n)^3$, and an optomechanical vacuum coupling rate of 310 kHz is measured. With optical quality factors up to $1.2 \\cdot 10^5$, fabricated devices are in the resolved-sideband regime. The electric field has its maximum at the slot wall and couples to the in-plane breathing motion of the slot. The optomechanical coupling is thus dominated by the moving-boundary effect, which we simulate to be six times greater than the photoelastic effect, in contrast to most structures, where the photoelastic effect is often the primary coupling mechanism.

  16. Resolution study of higher-order-mode-based beam position diagnostics using custom-built electronics in strongly coupled 3.9-GHz multi-cavity accelerating module

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, P.; Baboi, N.; Jones, R.M.; Eddy, N.

    2012-11-01

    Beam-excited higher order modes (HOMs) can provide remote diagnostics information of the beam position and cavity misalignment. In this paper we report on recent studies on the resolution with specially selected series of modes with custom-built electronics. This constitutes the first report of measurements of these cavities in which we obtained a resolution of 20 micron in beam offset. Details of the setup of the electronics and HOM measurements are provided.

  17. Analysis and evaluation of RF absorbing material in suppressing modes associated with a metallic cavity

    Science.gov (United States)

    Green, David L.

    Application of absorbing materials within enclosures designed to house high-speed digital electronics has become common practice for suppressing resonances associated with the enclosure geometry. Use of absorbing material is often considered toward the end of the design phase when the product is undergoing electromagnetic compatibility compliance testing, leaving little time for the additional experimentation required to optimize absorber material selection or placement within the device. The engineering principles required for maximizing absorber performance within the enclosure are often disregarded, replaced by a "shotgun" approach where multiple material options are experimented with until a solution is achieved. For this research a frequency domain reverberation chamber technique and one-port time domain quality factor estimation technique are employed to quantify the ability of various absorbing materials to suppress resonances of a physically small, electrically large cavity representative of those that may be used to enclose high-speed circuitry. Using both measurement techniques, assessment of the performance of various absorbing materials was performed as well as an evaluation of the affect absorber position has on overall material performance. It was found that both measurement techniques were effective in quantifying absorber performance within the cavity. For the frequency domain reverberation chamber approach the absorber effectiveness, defined as the difference in insertion loss between the cavity with and without absorbing material, was analyzed for various materials. For the undermoded cavity it was found that absorber effectiveness was positionally dependent. For the overmoded cavity, however, the position of the absorber within the cavity, as long as the total exposed surface area remained constant, did not have a significant impact on the absorber effectiveness. Similar results were also found by comparing the estimated quality factor for

  18. Geometric phase and o-mode blueshift in a chiral anisotropic medium inside a Fabry-Pérot cavity.

    Science.gov (United States)

    Timofeev, Ivan V; Gunyakov, Vladimir A; Sutormin, Vitaly S; Myslivets, Sergey A; Arkhipkin, Vasily G; Vetrov, Stepan Ya; Lee, Wei; Zyryanov, Victor Ya

    2015-11-01

    Anomalous spectral shift of transmission peaks is observed in a Fabry-Pérot cavity filled with a chiral anisotropic medium. The effective refractive index value resides out of the interval between the ordinary and the extraordinary refractive indices. The spectral shift is explained by contribution of a geometric phase. The problem is solved analytically using the approximate Jones matrix method, numerically using the accurate Berreman method, and geometrically using the generalized Mauguin-Poincaré rolling cone method. The o-mode blueshift is measured for a 4-methoxybenzylidene-4'-n-butylaniline twisted-nematic layer inside the Fabry-Pérot cavity. The twist is electrically induced due to the homeoplanar-twisted configuration transition in an ionic-surfactant-doped liquid crystal layer. Experimental evidence confirms the validity of the theoretical model.

  19. The binding cavity of mouse major urinary protein is optimised for a variety of ligand binding modes

    Energy Technology Data Exchange (ETDEWEB)

    Pertinhez, Thelma A.; Ferrari, Elena; Casali, Emanuela [Department of Experimental Medicine, University of Parma, Via Volturno, 39, 43100 Parma (Italy); Patel, Jital A. [Department of Chemistry, University of Oxford, Inorganic Chemistry Laboratory, South Parks Road, Oxford OX1 3QR (United Kingdom); Spisni, Alberto, E-mail: alberto.spisni@unipr.it [Department of Experimental Medicine, University of Parma, Via Volturno, 39, 43100 Parma (Italy); Smith, Lorna J., E-mail: lorna.smith@chem.ox.ac.uk [Department of Chemistry, University of Oxford, Inorganic Chemistry Laboratory, South Parks Road, Oxford OX1 3QR (United Kingdom)

    2009-12-25

    {sup 15}N and {sup 1}HN chemical shift data and {sup 15}N relaxation studies have been used to characterise the binding of N-phenyl-naphthylamine (NPN) to mouse major urinary protein (MUP). NPN binds in the {beta}-barrel cavity of MUP, hydrogen bonding to Tyr120 and making extensive non-bonded contacts with hydrophobic side chains. In contrast to the natural pheromone 2-sec-butyl-4,5-dihydrothiazole, NPN binding gives no change to the overall mobility of the protein backbone of MUP. Comparison with 11 different ligands that bind to MUP shows a range of binding modes involving 16 different residues in the {beta}-barrel cavity. These finding justify why MUP is able to adapt to allow for many successful binding partners.

  20. Geometric phase and o-mode blue shift in a chiral anisotropic medium inside a Fabry-P\\'erot cavity

    CERN Document Server

    Timofeev, I V; Sutormin, V S; Myslivets, S A; Arkhipkin, V G; Vetrov, S Ya; Lee, W; Zyryanov, V Ya

    2015-01-01

    Anomalous spectral shift of transmission peaks is observed in a Fabry--P\\'erot cavity filled with a chiral anisotropic medium. The effective refractive index value resides out of the interval between the ordinary and the extraordinary refractive indices. The spectral shift is explained by contribution of a geometric phase. The problem is solved analytically using the approximate Jones matrix method, numerically using the accurate Berreman method and geometrically using the generalized Mauguin--Poincar\\'e rolling cone method. The $o$-mode blue shift is measured for a 4-methoxybenzylidene-4'-$n$-butylaniline twisted--nematic layer inside the Fabry--P\\'erot cavity. The twist is electrically induced due to the homeoplanar--twisted configuration transition in an ionic-surfactant-doped liquid crystal layer. Experimental evidence confirms the validity of the theoretical model.

  1. Controllable optical response by modifying the gain and loss of a mechanical resonator and cavity mode in an optomechanical system

    CERN Document Server

    Liu, Yu-Long; Zhang, Jing; Özdemir, Şahin Kaya; Yang, Lan; Nori, Franco; Liu, Yu-xi

    2016-01-01

    We theoretically study a strongly-driven optomechanical system which consists of a passive optical cavity and an active mechanical resonator. When the optomechanical coupling strength is varied, phase transitions, which are similar those observed in $\\mathcal{PT}$-symmetric systems, are observed. We show that the optical transmission can be controlled by changing the gain of the mechanical resonator and loss of the optical cavity mode. Especially, we find that: (i) for balanced gain and loss, optical amplification and absorption can be tuned by changing the optomechanical coupling strength through a control field; (ii) for unbalanced gain and loss, even with a tiny mechanical gain, both optomechanically-induced transparency and anomalous dispersion can be observed around a critical point, which exhibits an ultra-long group delay. The time delay $\\tau$ can be optimized by regulating the optomechanical coupling strength through the control field and improved up to several orders of magnitude ($\\tau\\sim2$ $\\math...

  2. Semi-analytical quasi-normal mode theory for the local density of states in coupled photonic crystal cavity-waveguide structures

    DEFF Research Database (Denmark)

    de Lasson, Jakob Rosenkrantz; Kristensen, Philip Trøst; Mørk, Jesper

    2015-01-01

    We present and validate a semi-analytical quasi-normal mode (QNM) theory for the local density of states (LDOS) in coupled photonic crystal (PhC) cavity-waveguide structures. By means of an expansion of the Green's function on one or a few QNMs, a closed-form expression for the LDOS is obtained......, and for two types of two-dimensional PhCs, with one and two cavities side-coupled to an extended waveguide, the theory is validated against numerically exact computations. For the single cavity, a slightly asymmetric spectrum is found, which the QNM theory reproduces, and for two cavities a non...

  3. Entanglement characteristics of subharmonic modes reflected from cavity for type II second harmonic generation

    CERN Document Server

    Zhai, Z; Gao, J; Zhai, Zehui; Li, Yongming; Gao, Jiangrui

    2004-01-01

    Quantum fluctuation and quantum entanglement of the pump field reflected from an optical cavity for type II second harmonic generation are theoretically analyzed. The correlation spectra between the quadratures of the reflected subharmonic fields are interpreted in terms of pump parameter, intracavity losses and normalized frequency. Large correlation degrees of both amplitude and phase quadratures can be accessed in a triple resonant cavity before the pitchfork bifurcation occurs. The two reflected subharmonic fields are in an entangled state with the quantum correlation of phase quadratures and anticorrelation of amplitude quadratures. The proposed system can be exploited to be a new source generating entangled states of continuous variables.

  4. A study of beam position diagnostics using beam-excited dipole modes in third harmonic superconducting accelerating cavities at a free-electron laser

    CERN Document Server

    Zhang, P; Jones, R M; Shinton, I R R; Flisgen, T; Glock, H W

    2012-01-01

    We investigate the feasibility of beam position diagnostics using Higher Order Mode (HOM) signals excited by an electron beam in the third harmonic 3.9 GHz superconducting accelerating cavities at FLASH. After careful theoretical and experimental assessment of the HOM spectrum, three modal choices have been narrowed down to fulfill different diagnostics requirements. These are localized dipole beam-pipe modes, trapped cavity modes from the fifth dipole band and propagating modes from the first two dipole bands. These modes are treated with various data analysis techniques: modal identification, direct linear regression (DLR) and singular value decomposition (SVD). Promising options for beam diagnostics are found from all three modal choices. This constitutes the first prediction, subsequently confirmed by experiments, of trapped HOMs in third harmonic cavities, and also the first direct comparison of DLR and SVD in the analysis of HOM-based beam diagnostics.

  5. A study of beam position diagnostics using beam-excited dipole modes in third harmonic superconducting accelerating cavities at a free-electron laser

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Pei [School of Physics and Astronomy, University of Manchester, Manchester M13 9PL (United Kingdom); Deutsches Elektronen-Synchrotron (DESY), 22607 Hamburg (Germany); Baboi, Nicoleta [Deutsches Elektronen-Synchrotron (DESY), 22607 Hamburg (Germany); Jones, Roger M.; Shinton, Ian R. R. [School of Physics and Astronomy, University of Manchester, Manchester M13 9PL (United Kingdom); Cockcroft Institute, Cheshire WA4 4AD (United Kingdom); Flisgen, Thomas; Glock, Hans-Walter [Institut fuer Allgemeine Elektrotechnik, Universitaet Rostock, 18051 Rostock (Germany)

    2012-08-15

    We investigate the feasibility of beam position diagnostics using higher order mode (HOM) signals excited by an electron beam in the third harmonic 3.9 GHz superconducting accelerating cavities at FLASH. After careful theoretical and experimental assessment of the HOM spectrum, three modal choices have been narrowed down to fulfill different diagnostics requirements. These are localized dipole beam-pipe modes, trapped cavity modes from the fifth dipole band, and propagating modes from the first two dipole bands. These modes are treated with various data analysis techniques: modal identification, direct linear regression (DLR), and singular value decomposition (SVD). Promising options for beam diagnostics are found from all three modal choices. This constitutes the first prediction, subsequently confirmed by experiments, of trapped HOMs in third harmonic cavities, and also the first direct comparison of DLR and SVD in the analysis of HOM-based beam diagnostics.

  6. Transverse Mode Structure and Pattern Formation in Oxide Confined Vertical Cavity Semiconductor Lasers

    Energy Technology Data Exchange (ETDEWEB)

    Choquette, K.D.; Geib, K.M.; Hegarty, S.P.; Hou, H.Q.; Huyet, G.; McInerney, J.G.; Porta, P.

    1999-07-06

    We analyze the transverse profiles of oxide-confined vertical cavity laser diodes as a function of aperture size. For small apertures we demonstrate that thermal lensing can be the dominant effect in determining the transverse resonator properties. We also analyze pattern formation in lasers with large apertures where we observe the appearance of tilted waves.

  7. Multiple Dissipative Solitons in a Long-Cavity Normal-Dispersion Mode-Locked Yb-Doped Fiber Laser

    Institute of Scientific and Technical Information of China (English)

    ZHAO Guang-Zhen; XIAO Xiao-Sheng; MEI Jia-Wei; YANG Chang-Xi

    2012-01-01

    Transitional operations of multiple dissipative solitons in a long-cavity normal-dispersion Yb-doped fiber laser are experimentally investigated.Multiple dissipative solitons,including a stable soliton pair and a soliton triplet are observed by increasing the pump power or adjusting the polarization controllers.Two main boundaries of the stable asymmetric soliton and oscillating soliton are found between steady mode-locking.Moreover,multiple dissipative solitons with greater quantities of solitons are observed with pump power increasing.The experimental results agree well with a previous numerical study of multiple dissipative solitons.

  8. Higher‐order mode absorption measurement of X-band choke-mode cavities in a radial line structure

    Energy Technology Data Exchange (ETDEWEB)

    Zha, Hao [Department of Engineering Physics, Tsinghua University, Beijing CN-100086 (China); Key Laboratory of Particle and Radiation Imaging, Tsinghua University, Ministry of Education, Beijing (China); The European Organization for Nuclear Research, Geneva CH-1211 (Switzerland); Shi, Jiaru, E-mail: shij@mail.tsinghua.edu.cn [Department of Engineering Physics, Tsinghua University, Beijing CN-100086 (China); Key Laboratory of Particle and Radiation Imaging, Tsinghua University, Ministry of Education, Beijing (China); The European Organization for Nuclear Research, Geneva CH-1211 (Switzerland); Wu, Xiaowei; Chen, Huaibi [Department of Engineering Physics, Tsinghua University, Beijing CN-100086 (China); Key Laboratory of Particle and Radiation Imaging, Tsinghua University, Ministry of Education, Beijing (China)

    2016-04-01

    An experiment is presented to study the higher-order mode (HOM) suppression of X-band choke-mode structures with a vector network analyzer (VNA). Specific radial line disks were built to test the reflection from the corresponding damping load and different choke geometries. The mismatch between the radial lines and the VNA was calibrated through a special multi-short-load calibration method. The measured reflections of different choke geometries showed good agreement with the theoretical calculations and verified the HOM absorption feature of each geometric design.

  9. Mapping of two-polarization-mode dynamics in vertical-cavity surface-emitting lasers with optical injection.

    Science.gov (United States)

    Gatare, I; Sciamanna, M; Nizette, M; Thienpont, H; Panajotov, K

    2009-08-01

    We report theoretically on the interplay between polarization switching and bifurcations to nonlinear dynamics in a vertical-cavity surface-emitting laser (VCSEL) subject to orthogonal optical injection. Qualitatively different bifurcation scenarios leading to polarization switching are found and mapped out in the plane of the injection parameters, i.e., the frequency detuning vs injection strength plane. A Hopf bifurcation mechanism on the two-polarization-mode solution determines the injection-locking boundaries and influences polarization switching induced by optical injection. We furthermore report on a torus bifurcation emerging from a two-linearly polarized (LP) mode time-periodic dynamics before polarization switching and injection locking appear. It corresponds to an interesting combination of relaxation oscillation dynamics in the x -LP mode together with wave mixing dynamics in the injected y -LP mode. In agreement with recent experiments, we unveil a period-doubling route to chaos that involves both VCSEL orthogonal LP modes. The corresponding region of chaotic dynamics coincides with abrupt changes in the polarization switching boundaries in the plane of the injection parameters.

  10. High-performance Refractive Index Sensor Based on Photonic Crystal Single Mode Resonant Micro-cavity

    Institute of Scientific and Technical Information of China (English)

    Shengye Huang; Junfeng Shi; Dongsheng Wang; Wei Li

    2006-01-01

    An effective refractive index sensor built with square lattice photonic crystal is proposed, which can be applicable to photonic integrated circuits. Two photonic crystal waveguides rather than conventional ridge waveguides are used as entrance/exit waveguides to the micro-cavity. Three layers of photonic lattice are set between the photonic crystal waveguides and the micro-cavity to achieve both a high transmission and a high sensitivity. The plane wave method is utilized to calculate the disperse curves and the finite difference time domain scheme is employed to simulate the light propagation. At the resonant wavelength of about 1500 nm, the resonant wavelength shifts up by 0.7 nm for each increment of △n=0.001. A transmission of more than 0.75 is observed. Although the position disorder of the photonic crystal doesn't affect the sensitivity of the sensor,the transmission reduces rapidly as the disorder increases.

  11. Highly efficient single-longitudinal-mode {beta}-BaB{sub 2}O{sub 4} optical parametric oscillator with a new cavity design

    Energy Technology Data Exchange (ETDEWEB)

    Boon-Engering, J.M. [Nederlands Centrum voor Laser Research b.v., Postbus 2662, 7500 CR Enschede (Netherlands)]|[Department of Physics and Astronomy, Laser Centre Vrije Universiteit, De Boelelaan 1081, 1081 HV Amsterdam (Netherlands); Gloster, L.A.W. [Laser Photonics Group, Department of Physics and Astronomy, University of Manchester, Manchester M13 9PL (United Kingdom); van der Veer, W.E. [Nederlands Centrum voor Laser Research b.v., Postbus 2662, 7500 CR Enschede (Netherlands)]|[Department of Physics and Astronomy, Laser Centre Vrije Universiteit, De Boelelaan 1081, 1081 HV Amsterdam (Netherlands); McKinnie, I.T. [Laser Photonics Group, Department of Physics and Astronomy, University of Manchester, Manchester M13 9PL (United Kingdom)]|[Department of Physics, University of Otago, P.O. Box 56, Dunedin (New Zealand); King, T.A. [Laser Photonics Group, Department of Physics and Astronomy, University of Manchester, Manchester M13 9PL (United Kingdom); Hogervorst, W. [Department of Physics and Astronomy, Laser Centre Vrije Universiteit, De Boelelaan 1081, 1081 HV Amsterdam (Netherlands)

    1995-10-15

    A new coupled-cavity design for single-longitudinal-mode operation of an optical parametric oscillator (OPO) is presented. The OPO is based on a {beta}-BaB{sub 2}O{sub 4} crystal and is pumped by the third harmonic of a Nd:YAG laser. With this design, we achieved single-longitudinal-mode operation of the OPO with a decrease in the threshold and an increase in external efficiency compared with those of a conventional grazing-incidence OPO. A mathematical model that describes the mode spacings for this cavity is given. {copyright} {ital 1995} {ital Optical} {ital Society} {ital of} {ital America}.

  12. Investigation of double-mode operation and fast fine tuning properties of a grating-coupled external cavity diode laser configuration

    Science.gov (United States)

    Bayrakli, Ismail

    2017-01-01

    Double-mode operation and fast piezo fine tuning properties of a gain chip on a thermoelectric cooler in an external cavity are investigated. A widely course double-mode tuning range of 120 nm for the spectral range between 1470 and 1590 nm is achieved by rotating the diffraction gratings forming a double Littrow-type configuration. A fast piezo fine tuning range over 7cm-1 (1.5 nm, 210 GHz) in a single-mode operation is obtained by scanning the external cavity length with scan rates up to 0.5 kHz.

  13. Optical mode confinement in three-dimensional Al/SiO2 nano-cavities with hyperbolic dispersion

    Science.gov (United States)

    Bacco, Carla; Kelly, Priscilla; Kuznetsova, Lyuba

    2015-09-01

    Today's technological needs are demanding for faster and smaller optical components. Optical microcavities offer a high confinement of electromagnetic field in a small volume, with dimensions comparable to the wavelength of light, which provides a unique system for the enhancement of light-matter interactions on the nanoscale. However, further reducing the size of the optical cavity (from microcavity to nanocavity) is limited to the fundamental diffraction limit. In hyperbolic metamaterials, large wave vectors can be achieved. Therefore, optical cavities, created from hyperbolic metamaterials, allow the confinement of the electromagnetic field to an extremely small volume with dimensions significantly smaller than the wavelength of light. This paper presents the results of numerical study of the optical mode confinement in nanocavities with hyperbolic dispersion using nanolayered Al/SiO2 hyperbolic metamaterial with different Al fill fractions. The fundamental properties of the optical modes and resonance frequencies for the nanocavities are studied using the finite-elementmethod numerical technique. Numerical simulations show that the light can be well confined in a disk with radius up to λ/65. This paper will also focus on other variables such as Q-factor and Al fill fraction. Potential future applications for three-dimensional nanocavities with hyperbolic dispersion include: silicon photonics optical communications networks, ultrafast LEDs and biological nanoparticles sensing.

  14. Thermal analysis of bulk filled composite resin polymerization using various light curing modes according to the curing depth and approximation to the cavity wall

    Directory of Open Access Journals (Sweden)

    Hoon-Sang Chang

    2013-07-01

    Full Text Available OBJECTIVE: The purpose of this study was to investigate the polymerization temperature of a bulk filled composite resin light-activated with various light curing modes using infrared thermography according to the curing depth and approximation to the cavity wall. MATERIAL AND METHODS: Composite resin (AeliteFlo, Bisco, Schaumburg, IL, USA was inserted into a Class II cavity prepared in the Teflon blocks and was cured with a LED light curing unit (Dr's Light, GoodDoctors Co., Seoul, Korea using various light curing modes for 20 s. Polymerization temperature was measured with an infrared thermographic camera (Thermovision 900 SW/TE, Agema Infra-red Systems AB, Danderyd, Sweden for 40 s at measurement spots adjacent to the cavity wall and in the middle of the cavity from the surface to a 4 mm depth. Data were analyzed according to the light curing modes with one-way ANOVA, and according to curing depth and approximation to the cavity wall with two-way ANOVA. RESULTS: The peak polymerization temperature of the composite resin was not affected by the light curing modes. According to the curing depth, the peak polymerization temperature at the depth of 1 mm to 3 mm was significantly higher than that at the depth of 4 mm, and on the surface. The peak polymerization temperature of the spots in the middle of the cavity was higher than that measured in spots adjacent to the cavity wall. CONCLUSION: In the photopolymerization of the composite resin, the temperature was higher in the middle of the cavity compared to the outer surface or at the internal walls of the prepared cavity.

  15. Thermal analysis of bulk filled composite resin polymerization using various light curing modes according to the curing depth and approximation to the cavity wall

    Science.gov (United States)

    CHANG, Hoon-Sang; CHO, Kyu-Jeong; PARK, Su-Jung; LEE, Bin-Na; HWANG, Yun-Chan; OH, Won-Mann; HWANG, In-Nam

    2013-01-01

    Objective The purpose of this study was to investigate the polymerization temperature of a bulk filled composite resin light-activated with various light curing modes using infrared thermography according to the curing depth and approximation to the cavity wall. Material and Methods Composite resin (AeliteFlo, Bisco, Schaumburg, IL, USA) was inserted into a Class II cavity prepared in the Teflon blocks and was cured with a LED light curing unit (Dr's Light, GoodDoctors Co., Seoul, Korea) using various light curing modes for 20 s. Polymerization temperature was measured with an infrared thermographic camera (Thermovision 900 SW/TE, Agema Infra-red Systems AB, Danderyd, Sweden) for 40 s at measurement spots adjacent to the cavity wall and in the middle of the cavity from the surface to a 4 mm depth. Data were analyzed according to the light curing modes with one-way ANOVA, and according to curing depth and approximation to the cavity wall with two-way ANOVA. Results The peak polymerization temperature of the composite resin was not affected by the light curing modes. According to the curing depth, the peak polymerization temperature at the depth of 1 mm to 3 mm was significantly higher than that at the depth of 4 mm, and on the surface. The peak polymerization temperature of the spots in the middle of the cavity was higher than that measured in spots adjacent to the cavity wall. Conclusion In the photopolymerization of the composite resin, the temperature was higher in the middle of the cavity compared to the outer surface or at the internal walls of the prepared cavity. PMID:24037066

  16. Intra-cavity gain shaping of mode-locked Ti:Sapphire laser oscillations

    CERN Document Server

    Yefet, Shai; Pe'er, Avi

    2015-01-01

    The gain properties of an oscillator strongly affect its behavior. When the gain is homogeneous, different modes compete for gain resources in a `winner takes all' manner, whereas with inhomogeneous gain, modes can coexist if they utilize different gain resources. We demonstrate precise control over the mode competition in a mode locked Ti:sapphire oscillator by manipulation and spectral shaping of the gain properties, thus steering the competition towards a desired, otherwise inaccessible, oscillation. Specifically, by adding a small amount of spectrally shaped inhomogeneous gain to the standard homogeneous gain oscillator, we selectively enhance a desired two-color oscillation, which is inherently unstable to mode competition and could not exist in a purely homogeneous gain oscillator. By tuning the parameters of the additional inhomogeneous gain we flexibly control the center wavelengths, relative intensities and widths of the two colors.

  17. Graded index profiles and loss-induced single-mode characteristics in vertical-cavity surface-emitting lasers with petal-shape holey structure

    Institute of Scientific and Technical Information of China (English)

    Liu An-Jin; Qu Hong-Wei; Chen Wei; Jiang Bin; Zhou Wen-Jun; Xing Ming-Xin; Zheng Wan-Hua

    2011-01-01

    The 850-nm oxide-confined vertical-cavity surface-emitting lasers with petal-shape holey structures are presented. An area-weighted average refractive index model is given to analyse their effective index profiles, and the graded index distribution in the holey region is demonstrated. The index step between the optical aperture and the holey region is obtained which is related merely to the etching depth. Four types of holey vertical-cavity surface-emitting lasers with different parameters are fabricated as well as the conventional oxide-confined vertical-cavity surface-emitting laser. Compared with the conventional oxide-confined vertical-cavity surface-emitting laser without etched holes, the holey vertical-cavity surface-emitting laser possesses an improved beam quality due to its graded index distribution, but has a lower output power, higher threshold current and lower slope efficiency. With the hole number increased, the holey vertical-cavity surface-emitting laser can realize the single-mode operation throughout the entire current range, and reduces the beam divergence further. The loss mechanism is used to explain the single-mode characteristic, and the reduced beam divergence is attributed to the shallow etching. High coupling efficiency of 86% to a multi-mode fibre is achieved for the single-mode device in the experiment.

  18. Room temperature low-threshold InAs/InP quantum dot single mode photonic crystal microlasers at 1.5 microm using cavity-confined slow light.

    Science.gov (United States)

    Bordas, Frédéric; Seassal, Christian; Dupuy, Emmanuel; Regreny, Philippe; Gendry, Michel; Viktorovitch, Pierre; Steel, M J; Rahmani, Adel

    2009-03-30

    We have designed, fabricated, and characterized an InP photonic crystal slab structure that supports a cavity-confined slow-light mode, i.e. a bandgap-confined valence band-edge mode. Three dimensional finite difference in time domain calculations predict that this type of structure can support electromagnetic modes with large quality factors and small mode volumes. Moreover these modes are robust with respect to fabrication imperfections. In this paper, we demonstrate room-temperature laser operation at 1.5 mum of a cavity-confined slow-light mode under pulsed excitation. The gain medium is a single layer of InAs/InP quantum dots. An effective peak pump power threshold of 80 microW is reported.

  19. The Deflection Question

    Science.gov (United States)

    Greenberg, A. H.; Nesvold, E.; van Heerden, E.; Erasmus, N.; Marchis, F.

    2016-12-01

    On 15 February, 2013, a 15 m diameter asteroid entered the Earth's atmosphere over Russia. The resulting shockwave injured nearly 1500 people, and incurred 33 million (USD) in infrastructure damages. The Chelyabinsk meteor served as a forceful demonstration of the threat posed to Earth by the hundreds of potentially hazardous objects (PHOs) that pass near the Earth every year. Although no objects have yet been discovered on an impact course for Earth, an impact is virtually statistically guaranteed at some point in the future. While many impactor deflection technologies have been proposed, humanity has yet to demonstrate the ability to divert an impactor when one is found. Developing and testing any single proposed technology will require significant research time and funding. This leaves open an obvious question - towards which technologies should funding and research be directed, in order to maximize our preparedness for when an impactor is eventually found? To help answer this question, we have created a detailed framework for analyzing various deflection technologies and their effectiveness. Using an n-body integrator (REBOUND), we have simulated the attempted deflections of a population of Earth-impacting objects with a variety of velocity perturbations (∂Vs), and measured the effects that these perturbations had on impact probability. We then mapped the ∂Vs applied in the orbital simulations to the technologies capable of achieving those perturbations, and analyzed which set of technologies would be most effective at preventing a PHO from impacting the earth. As a final step, we used the results of these simulations to train a machine learning algorithm. This algorithm, combined with a simulated PHO population, can predict which technologies are most likely to be needed. The algorithm can also reveal which impactor observables (mass, spin, orbit, etc.) have the greatest effect on the choice of deflection technology. These results can be used as a tool to

  20. Theory and Modeling of Lasing Modes in Vertical Cavity Surface Emitting Lasers

    Directory of Open Access Journals (Sweden)

    Benjamin Klein

    1998-01-01

    modes that the VCSEL can support are then determined by matching the gain necessary for the optical system in both magnitude and phase to the gain available from the laser's electronic system. Examples are provided.

  1. Formation of long-lived resonances in hexagonal cavities by strong coupling of superscar modes

    Science.gov (United States)

    Song, Qinghai; Ge, Li; Wiersig, Jan; Cao, Hui

    2013-08-01

    The recent progresses in single crystalline wide bandgap hexagonal disk have stimulated intense research attention on pursuing ultraviolet (UV) laser diodes with low thresholds. While whispering-gallery modes based UV lasers have been successfully obtained in GaN, ZnO nanorods, and nanopillars, the reported thresholds are still very high, due to the low-quality (Q) factors of the hexagonal resonances. Here we demonstrate resonances whose Q factors can be more than two orders of magnitude higher than the hexagonal modes, promising the reduction of the energy consumption. The key to our finding is the avoided resonance crossing between superscar states along two sets of nearly degenerated triangle orbits, which leads to the formation of hexagram modes. The mode couplings suppress the field distributions at the corners and the deviations from triangle orbits simultaneously and therefore enhance the Q factors significantly.

  2. Band gaps and cavity modes in dual phononic and photonic strip waveguides

    Directory of Open Access Journals (Sweden)

    Y. Pennec

    2011-12-01

    Full Text Available We discuss theoretically the simultaneous existence of phoxonic, i.e., dual phononic and photonic, band gaps in a periodic silicon strip waveguide. The unit-cell of this one-dimensional waveguide contains a hole in the middle and two symmetric stubs on the sides. Indeed, stubs and holes are respectively favorable for creating a phononic and a photonic band gap. Appropriate geometrical parameters allow us to obtain a complete phononic gap together with a photonic gap of a given polarization and symmetry. The insertion of a cavity inside the perfect structure provides simultaneous confinement of acoustic and optical waves suitable to enhance the phonon-photon interaction.

  3. Graphene mode-locked multipass-cavity femtosecond Cr4+: forsterite laser

    OpenAIRE

    Baylam, Işınsu; Çizmeciyan, Melisa Natali; Sennaroğlu, Alphan; Ozharar, Sarper; Balcı, Osman; Pince, Ercag; Kocabaş, Coşkun

    2013-01-01

    We report, for the first time to our knowledge, the use of graphene as a saturable absorber in an energy-scaled femtosecond Cr4+: forsterite laser. By incorporating a multipass cavity, the repetition rate of the original short resonator was reduced to 4.51 MHz, which resulted in the generation of 100 fs, nearly transform-limited pulses at 1252 nm with a peak power of 53 kW. To the best of our knowledge, this is the highest peak power obtained from a room-temperature, femtosecond Cr4+: forster...

  4. GHz-bandwidth upconversion detector using a unidirectional ring cavity to reduce multilongitudinal mode pump effects

    DEFF Research Database (Denmark)

    Meng, Lichun; Høgstedt, Lasse; Tidemand-Lichtenberg, Peter

    2017-01-01

    narrow-linewidth lasers in a fiber coupler while tuning their wavelength difference down to 10 pm or less. The SFG crystal is placed inside an Nd:YVO4 ring cavity that provides 1064 nm circulating pump powers of up to 150 W in unidirectional operation. Measured Fabry-Perot spectrum at 1064 nm confirms...... for cooling, the GHz-bandwidth upconverter can readily be extended to the mid-IR (2 - 5 mu m) as an alternative to cooled low-bandgap semiconductor detectors for applications such as high-speed free-space optical communications. (C) 2017 Optical Society of America...

  5. Analytic modeling of instabilities driven by higher-order modes in the HLS Ⅱ RF system with a higher-harmonic cavity

    Institute of Scientific and Technical Information of China (English)

    ZHAO Yu-Ning; LI Wei-Min; WU Cong-Feng; WANG Lin

    2013-01-01

    The utility of a passive fourth-harmonic cavity plays a key role in suppressing longitudinal beam instabilities in the electron storage ring and lengthens the bunch by a factor of 2.6 for the phase Ⅱ project of the Hefei Light Source (HLS Ⅱ).Meanwhile,instabilities driven by higher-order modes (HOM) may limit the performance of the higher-harmonic cavity.In this paper,the parasitic coupled-bunch instability,which is driven by narrow band parasitic modes,and the microwave instability,which is driven by broadband HOM,are both modeled analytically.The analytic modeling results are in good agreement with those of our previous simulation study and indicate that the passive fourth-harmonic cavity suppresses parasitic coupled-bunch instabilities and microwave instability.The modeling suggests that a fourth-harmonic cavity may be successfully used at the HLS Ⅱ.

  6. Determination of the quasi-TE mode (in-plane) graphene linear absorption coefficient via integration with silicon-on-insulator racetrack cavity resonators.

    Science.gov (United States)

    Crowe, Iain F; Clark, Nicholas; Hussein, Siham; Towlson, Brian; Whittaker, Eric; Milosevic, Milan M; Gardes, Frederic Y; Mashanovich, Goran Z; Halsall, Matthew P; Vijayaraghaven, Aravind

    2014-07-28

    We examine the near-IR light-matter interaction for graphene integrated cavity ring resonators based on silicon-on-insulator (SOI) race-track waveguides. Fitting of the cavity resonances from quasi-TE mode transmission spectra reveal the real part of the effective refractive index for graphene, n(eff) = 2.23 ± 0.02 and linear absorption coefficient, α(gTE) = 0.11 ± 0.01dBμm(-1). The evanescent nature of the guided mode coupling to graphene at resonance depends strongly on the height of the graphene above the cavity, which places limits on the cavity length for optical sensing applications.

  7. Analytic modeling of instabilities driven by higher-order modes in HLS II RF system with a higher-harmonic cavity

    CERN Document Server

    Zhao, Yuning; Wu, Congfeng; Wang, Lin

    2013-01-01

    The utility of a passive fourth-harmonic cavity plays key role in suppressing longitudinal beam instabilities in the electron storage ring and lengthens the bunch by a factor of 2.6 for the phase II project of Hefei Light Source(HLS II). Meanwhile, instabilities driven by higher-order modes(HOM) may limit the performance of the higher-harmonic cavity. In this paper, the parasitic coupled-bunch instability which is driven by narrow band parasitic modes and the microwave instability which is driven by broadband HOM are both modeled analytically. The analytic modeling results are in good agreement with that of our previous simulation study and indicate that the passive fourth-harmonic cavity suppresses parasitic coupled-bunch instabilities and the microwave instability. The modeling suggests that a fourth-harmonic cavity may be successfully used at HLS II.

  8. Mode stability analysis in the beam-wave interaction process for a three-gap Hughes-type coupled cavity chain

    Institute of Scientific and Technical Information of China (English)

    Luo Ji-Run; Cui Jian; Zhu Min; Guo Wei

    2013-01-01

    Based on space-charge wave theory,the formulae of the beam-wave coupling coefficient and the beam-loaded conductance are given for the beam-wave interaction in an N-gap Hughes-type coupled cavity chain.The ratio of the nonbeam-loaded quality factor of the coupled cavity chain to the beam quality factor is used to determine the stability of the beam-wave interaction.As an example,the stabilities of the beam-wave interaction in a three-gap Hughes-type coupled cavity chain are discussed with the formulae and the CST code for the operations of the 2π,π,and π/2 modes,respectively.The results show that stable operation of the 2π,π,and π/2 modes may all be realized in an extended-interaction klystron with the three-gap Hughes-type coupled cavity chain.

  9. Passively Q-switched laser with single longitudinal mode based on the frequency selection of grating and F-P etalon in twisted-mode folded cavity

    Institute of Scientific and Technical Information of China (English)

    Bao'an Song; Weijiang Zhao; Deming Ren; Yanchen Qu; Heyong Zhang; Liming Qian; Xiaoyong Hu

    2009-01-01

    A passively Q-switched side-pumped laser with folded resonator is specially constructed for singlelongitudinal-mode smooth pulse output.Nd:YAG is chosen as the laser active medium and Cr4+:YAG as the saturable absorber medium.Additionally,the method of frequency selection by grating with 1200 line/mm and Fabry-Perot(F-P)etalon is used in the twisted-mode cavity.The single-frequency smooth pulses are produced with 10-Hz repetition rate,20-ns pulse width,and 1.064-μm wavelength.The probability of single-frequency laser output measured is over 99% by using the methods of Fourier analysis and F-P etalon multiple-beam interferometry at the threshold voltage.The measured near-field and far-field angles of divergence axe 1.442 and 1.315 mrad,respectively.The values of M2 are 1.32 and 1.31 separately with the knife-edge method.Single pulse at 1.064 μm with the energy of 8.8 mJ is achieved in TEM00 mode.

  10. Two-Dimensional Cavity Resonant Modes of Si Based Bragg Reflection Ridge Waveguide

    Institute of Scientific and Technical Information of China (English)

    CHEN San; Lu Hong-Yan; CHEN Kun-Ji; XU Jun; MA Zhong-Yuan; LI Wei; HUANG Xin-Fan

    2011-01-01

    @@ Si-based ridge-waveguides with Bragg reflectors are fabricated based on our method.Three resonant peaks could be obviously identified from the photoluminescence spectra, and field patterns of these resonant peaks, simulated by the finite difference time domain (FDTD) method, confirm that these peaks originate from cavity resonances.The resonant wavelengths and spatial angular distribution are given by the resonant models, which agree well with the experimental data.Experimentally, a simple method is proposed to testify the experimental and theoretical results.Such devices based on Bragg reflectors may have potential applications in light-emitting diodes, lasers and integrated photonic circuits.%Si-based ridge-waveguides with Bragg reflectors are fabricated based on our method. Three resonant peaks could be obviously identified from the photoluminescence spectra, and field patterns of these resonant peaks, simulated by the finite difference time domain (FDTD) method, confirm that these peaks originate from cavity resonances. The resonant wavelengths and spatial angular distribution are given by the resonant models, which agree well with the experimental data. Experimentally, a simple method is proposed to testify the experimental and theoretical results. Such devices based on Bragg reflectors may have potential applications in light-emitting diodes, lasers and integrated photonic circuits.

  11. All-solid-state cavity QED using Anderson-localized modes in disordered photonic crystal waveguides

    DEFF Research Database (Denmark)

    Lodahl, Peter; Sapienza, Luca; Nielsen, Henri Thyrrestrup;

    2010-01-01

    We employ Anderson-localized modes in deliberately disordered photonic crystal waveguides to confine light and enhance the interaction with matter. A 15-fold enhancement of the decay rate of a single quantum dot is observed meaning that 94% of the emitted single photons are coupled to an Anderson...

  12. Controllable optical response by modifying the gain and loss of a mechanical resonator and cavity mode in an optomechanical system

    Science.gov (United States)

    Liu, Yu-Long; Wu, Rebing; Zhang, Jing; Özdemir, Şahin Kaya; Yang, Lan; Nori, Franco; Liu, Yu-xi

    2017-01-01

    We theoretically study a strongly driven optomechanical system which consists of a passive optical cavity and an active mechanical resonator. When the optomechanical coupling strength is varied, phase transitions, which are similar to those observed in PT -symmetric systems, are observed. We show that the optical transmission can be controlled by changing the gain of the mechanical resonator and loss of the optical cavity mode. Especially, we find that (i) for balanced gain and loss, optical amplification and absorption can be tuned by changing the optomechanical coupling strength through a control field; (ii) for unbalanced gain and loss, even with a tiny mechanical gain, both optomechanically induced transparency and anomalous dispersion can be observed around a critical point, which exhibits an ultralong group delay. The time delay τ can be optimized by regulating the optomechanical coupling strength through the control field, and it can be improved up to several orders of magnitude (τ ˜2 ms ) compared to that of conventional optomechanical systems (τ ˜1 μ s ). The presence of mechanical gain makes the group delay more robust to environmental perturbations. Our proposal provides a powerful platform to control light transport using a PT -symmetric-like optomechanical system.

  13. Production of Squeezed State of Single Mode Cavity Field by the Coupling of Squeezed Vacunm Field Reservoir in Nonautonomous Case

    Institute of Scientific and Technical Information of China (English)

    安钧鸿; 王顺金; 罗洪刚; 贾成龙

    2004-01-01

    The dissipative and decoherence properties as well as the asymptotic behaviour of the single mode electromagnetic field interacting with the time-dependent squeezed vacuum field reservoir are investigated in detail by using the algebraic dynamical method. With the help of the left and right representations of the relevant hw( 4) algebra, the dynamical symmetry of the nonautonomous master equation of the system is found to be su(1, 1). The unique equilibrium steady solution is found to be the squeezed state and any initial state of the system is proven to approach the unique squeezed state asymptotically. Thus the squeezed vacuum field reservoir is found to play the role of a squeezing mold of the cavity field.

  14. Frequency tuning of the whispering-gallery modes of silica microspheres for cavity quantum electrodynamics and spectroscopy.

    Science.gov (United States)

    von Klitzing, W; Long, R; Ilchenko, V S; Hare, J; Lefèvre-Seguin, V

    2001-02-01

    We have tuned the whispering-gallery modes of a fused-silica microresonator over nearly 1 nm at 800 nm, i.e., over half a free spectral range, or 10(6) linewidths of the resonator. This result has been achieved by use of a new method based on the stretching of a two-stem microsphere. We describe devices that will permit new cavity QED experiments with this high- Q optical resonator when it is desirable to optimize its coupling to emitters with given transition frequencies. The demonstrated tuning capability is compatible with both UHV and low-temperature operation, which should be useful for future experiments with laser-cooled atoms or single quantum dots.

  15. Effect of Cavity Decay on Entanglement of Ladder-Type Three-Level Atoms and a Two-Mode Cavity Field

    Institute of Scientific and Technical Information of China (English)

    GAO Cheng-Yuan; LIU Jin-Ming; MA Lei

    2008-01-01

    Considering the adiabatical approximation and the large detuning condition, we give the effective Hamil-tonian of a ladder-type three levels atom interacting with a bimodal cavity field. If two identical three-level atoms are sent through the cavity one by one, a two-atom entangled state can be generated. With the choice of the appropriate interaction time, a maximally entangled state of two atoms can be obtained if decoherence effect is ignored. Moreover, we discuss the effect of cavity decay on four physical quantities including atomic population probability, residual entan-glement of the first atom and the cavity field, concurrence between the two atoms, and fidelity for generating atomic EPR state, all of which decrease with the increase of cavity decay when the other parameters are fixed.

  16. The Study on the Variation of the Cavity Length's Influence on the Output Pulse Train of the Actively Mode-Locked Fiber Laser

    Institute of Scientific and Technical Information of China (English)

    LUO Hong-e; TIAN Xiao-jian; GAO Bo

    2005-01-01

    The influence of actively mode-locked Erbium-Doped Fiber Laser(EDFL) cavity length variation on the noises of an optical pulse train is investigated, in theory and in MATLAB simulation. Using a simple model, the noise characteristics of the output pulse train are studied. The results show that the noises of the output pulse train increase with the increasing of the variation of the cavity length. The theory analysis and the simulation results agree well. This result is very significant for us to improve the reliability and the stability of the actively mode-locked fiber laser.

  17. Microwave band gap and cavity mode in spoof-insulator-spoof waveguide with multiscale structured surface

    CERN Document Server

    Zhang, Qiang; Han, Dezhuan; Qin, Fei Fei; Zhang, Xiao Ming; Yao, Yong

    2015-01-01

    We propose a multiscale spoof-insulator-spoof (SIS) waveguide by introducing periodic geometry modulation in the wavelength scale to a SIS waveguide made of perfect electric conductor. The MSIS consists of multiple SIS subcells. The dispersion relationship of the fundamental guided mode of the spoof surface plasmon polaritons (SSPPs) is studied analytically within the small gap approximation. It is shown that the multiscale SIS possesses microwave band gap (MBG) due to the Bragg scattering. The "gap maps" in the design parameter space are provided. We demonstrate that the geometry of the subcells can efficiently adjust the effective refraction index of the elementary SIS and therefore further control the width and the position of the MBG. The results are in good agreement with numerical calculations by the finite element method (FEM). For finite-sized MSIS of given geometry in the millimeter scale, FEM calculations show that the first-order symmetric SSPP mode has zero transmission in the MBG within frequency...

  18. Cuspal deflection and microleakage in premolar teeth restored with bulk-fill flowable resin-based composite base materials

    DEFF Research Database (Denmark)

    Moorthy, A; Hogg, C H; Dowling, A H;

    2012-01-01

    To assess the cuspal deflection and cervical microleakage of standardised Class II cavities incrementally filled with a dimethacrylate RBC or bulk-fill flowable RBC bases.......To assess the cuspal deflection and cervical microleakage of standardised Class II cavities incrementally filled with a dimethacrylate RBC or bulk-fill flowable RBC bases....

  19. Multi-mode competition in an FEL oscillator at perfect synchronism of an optical cavity

    CERN Document Server

    Dong, Z W; Kii, T; Yamazaki, T; Yoshikawa, K

    2002-01-01

    The sustained saturation in a short pulse free electron laser (FEL) oscillator at perfect synchronism of an optical cavity has been observed recently by Japan Atomic Energy Research Institute (JAERI) FEL group by using their super-conducting linac (Phys. Rev. Lett., in preparation). The experiments have clearly shown that FEL efficiency becomes maximum at perfect synchronism, although it has been considered that only a transient state exists at perfect synchronism due to the lethargy effect. Through careful analyses of the experimental condition of JAERI FEL, we found that, in spite of the short length of the electron micro-bunch, the saturation appears due to the following features, which were different from other FEL experiments: (1) very large ratio of the small signal gain to losses, (2) very long electron macro-bunch which can tolerate a slow start up. The saturation and high efficiency at perfect synchronism were benefited from the contribution of the weak sideband instability. In order to analyse these...

  20. Analysis of timing jitter in external-cavity mode-locked semiconductor lasers

    DEFF Research Database (Denmark)

    Mulet, Josep; Mørk, Jesper

    2006-01-01

    processes, self-phase modulation, and spontaneous emission noise. Fluctuations of the mode-locked pulses are characterized from the fully distributed model using direct integration of noise-skirts in the phase-noise spectrum and the soliton perturbations introduced by Haus. We implement the model in order...... to investigate the performance of a MQW buried heterostructure laser. Results from numerical simulations show that the optimum driving conditions for achieving the shortest pulses with minimum timing jitter occur for large reverse bias in the absorber section at an optimum optical bandwidth limited by Gordon...

  1. Temporal coupled mode analysis of one-dimensional magneto-photonic crystals with cavity structures

    Science.gov (United States)

    Saghirzadeh Darki, Behnam; Zeidaabadi Nezhad, Abolghasem; Firouzeh, Zaker Hossein

    2016-12-01

    In this paper, we propose the time-dependent coupled mode analysis of one-dimensional magneto-photonic crystals including one, two or multiple defect layers. The performance of the structures, namely the total transmission, Faraday rotation and ellipticity, is obtained using the proposed method. The results of the developed analytic approach are verified by comparing them to the results of the exact numerical transfer matrix method. Unlike the widely used numerical method, our proposed analytic method seems promising for the synthesis as well as the analysis purposes. Moreover, the proposed method has not the restrictions of the previously examined analytic methods.

  2. Retrieving the spatial distribution of cavity modes in dielectric resonators by near-field imaging and electrodynamics simulations.

    Science.gov (United States)

    Goñi, Alejandro R; Güell, Frank; Pérez, Luis A; López-Vidrier, Julian; Ossó, J Oriol; Coronado, Eduardo A; Morante, Joan R

    2012-03-01

    For good performance of photonic devices whose working principle is based on the enhancement of electromagnetic fields obtained by confining light into dielectric resonators with dimensions in the nanometre length scale, a detailed knowledge of the optical mode structure becomes essential. However, this information is usually lacking and can only be indirectly obtained by conventional spectroscopic techniques. Here we unraveled the influence of wire size, incident wavelength, degree of polarization and the presence of a substrate on the optical near fields generated by cavity modes of individual hexagonal ZnO nanowires by combining scanning near-field optical microscopy (SNOM) with electrodynamics calculations within the discrete dipole approximation (DDA). The near-field patterns obtained with very high spatial resolution, better than 50 nm, exhibit striking size and spatial-dispersion effects, which are well accounted for within DDA, using a wavevector-dependent dipolar interaction and considering the dielectric anisotropy of ZnO. Our results show that both SNOM and DDA simulations are powerful tools for the design of optoelectronic devices able to manipulate light at the nanoscale.

  3. External cavity based single mode Fabry-Pérot laser diode and its application towards all-optical digital circuits

    Science.gov (United States)

    Nakarmi, Bikash; Zhang, Xuping; Won, Yong Hyub

    2012-11-01

    We have proposed a novel approach of realizing all-optical logic gates and combinational circuit using external cavity based single mode Fabry-Pérot laser diodes (SMFP-LDs). Different techniques and critical parameters for injection locking the any one of the modes of SMFP-LDs are discussed. Taking consideration of wavelength detuning and input injected power, we have proposed and demonstrated multi-input injection locking, supporting beam injection locking with the conventional injection locking which are used for demonstrating different logic gates (NAND, AND, XNOR, XOR, NOT, NOR) and digital circuits (Half adder and Comparator). Since we have used SMFP-LDs, there is no requirement of additional probe beam and associated components as required by other optical technologies making the realization simple in configuration, cost effective and power efficient. Clear output waveforms, eye diagrams, risingfalling times and BER are presented to verify the proposed method. All-optical logic units and digital circuit are demonstrated at the data rate of 10 Gbps with the waveform of NRZ signal waveform and measured eye diagram and BER of the PRBS of 231-1 signal. The maximum power penalty among all demonstrated units is below 1.4 dB at the BER of 10-9.

  4. Quantum-coherent coupling of a mechanical oscillator to an optical cavity mode.

    Science.gov (United States)

    Verhagen, E; Deléglise, S; Weis, S; Schliesser, A; Kippenberg, T J

    2012-02-01

    Optical laser fields have been widely used to achieve quantum control over the motional and internal degrees of freedom of atoms and ions, molecules and atomic gases. A route to controlling the quantum states of macroscopic mechanical oscillators in a similar fashion is to exploit the parametric coupling between optical and mechanical degrees of freedom through radiation pressure in suitably engineered optical cavities. If the optomechanical coupling is 'quantum coherent'--that is, if the coherent coupling rate exceeds both the optical and the mechanical decoherence rate--quantum states are transferred from the optical field to the mechanical oscillator and vice versa. This transfer allows control of the mechanical oscillator state using the wide range of available quantum optical techniques. So far, however, quantum-coherent coupling of micromechanical oscillators has only been achieved using microwave fields at millikelvin temperatures. Optical experiments have not attained this regime owing to the large mechanical decoherence rates and the difficulty of overcoming optical dissipation. Here we achieve quantum-coherent coupling between optical photons and a micromechanical oscillator. Simultaneously, coupling to the cold photon bath cools the mechanical oscillator to an average occupancy of 1.7 ± 0.1 motional quanta. Excitation with weak classical light pulses reveals the exchange of energy between the optical light field and the micromechanical oscillator in the time domain at the level of less than one quantum on average. This optomechanical system establishes an efficient quantum interface between mechanical oscillators and optical photons, which can provide decoherence-free transport of quantum states through optical fibres. Our results offer a route towards the use of mechanical oscillators as quantum transducers or in microwave-to-optical quantum links.

  5. Semi-analytical quasi-normal mode theory for the local density of states in coupled photonic crystal cavity-waveguide structures

    CERN Document Server

    de Lasson, Jakob Rosenkrantz; Mørk, Jesper; Gregersen, Niels

    2015-01-01

    We present and validate a semi-analytical quasi-normal mode (QNM) theory for the local density of states (LDOS) in coupled photonic crystal (PhC) cavity-waveguide structures. By means of an expansion of the Green's function on one or a few QNMs, a closed-form expression for the LDOS is obtained, and for two types of two-dimensional PhCs, with one and two cavities side-coupled to an extended waveguide, the theory is validated against numerically exact computations. For the single cavity, a slightly asymmetric spectrum is found, which the QNM theory reproduces, and for two cavities a non-trivial spectrum with a peak and a dip is found, which is reproduced only when including both the two relevant QNMs in the theory. In both cases, we find relative errors below 1% in the bandwidth of interest.

  6. The influence of cavity preparation design on fracture strength and mode of fracture of laboratory-processed composite resin restorations.

    Science.gov (United States)

    Fonseca, Rodrigo Borges; Fernandes-Neto, Alfredo Julio; Correr-Sobrinho, Lourenco; Soares, Carlos Jose

    2007-10-01

    Removal of large amounts of sound tooth structure may result in a weakened restored tooth. Nevertheless, removal of tooth structure for cuspal coverage has been recommended to protect teeth restored with laboratory-processed composite resin (LPCR) from fracture. The purpose of this study was to evaluate the influence of different cavity preparation designs on fracture strength and modes of fracture of teeth restored with LPCR. Ninety anatomically similar human third mandibular molars were selected. There were 2 experimental factors, occlusal isthmus width (narrow versus wide) and cuspal coverage (inlay, 1-cusp onlay, 2-cusp onlay, and all-cusp onlay), and 1 control group that received no treatment, resulting in 9 groups (n=10). Indirect composite resin (SR Adoro) restorations were manufactured and adhesively cemented with Adper Single Bond 2 and Rely-X ARC. A compressive loading test (0.5 mm/min) was performed. The modes of fracture were classified according to 4 categories. One-way and 2-way ANOVA followed by Tukey-HSD test were used to statistically analyze the fracture load data (alpha =.05). The statistical analysis failed to show significant differences among restored groups but showed differences between these groups and the control group (P = .001). Two-way ANOVA failed to show any difference when considering the occlusal isthmus width alone (P = .98), cuspal coverage (P = .273), or the interaction between these factors (P = .972). Several teeth had fractures affecting a great amount of both restoration and tooth structure. This in vitro study showed restored teeth having similar fracture strength and fracture modes, suggesting that with the tested preparation designs, there is no advantage of cuspal coverage to protect LPCR restored teeth from fracture.

  7. Quantum-coherent coupling of a mechanical oscillator to an optical cavity mode

    CERN Document Server

    Verhagen, E; Weis, S; Schliesser, A; Kippenberg, T J

    2011-01-01

    Quantum control of engineered mechanical oscillators can be achieved by coupling the oscillator to an auxiliary degree of freedom, provided that the coherent rate of energy exchange exceeds the decoherence rate of each of the two sub-systems. We achieve such quantum-coherent coupling between the mechanical and optical modes of a micro-optomechanical system. Simultaneously, the mechanical oscillator is cooled to an average occupancy of n = 1.7 \\pm 0.1 motional quanta. Pulsed optical excitation reveals the exchange of energy between the optical light field and the micromechanical oscillator in the time domain at the level of less than one quantum on average. These results provide a route towards the realization of efficient quantum interfaces between mechanical oscillators and optical fields.

  8. Tailoring optical resonant cavity modes in SnO2 microstructures through doping and shape engineering

    Science.gov (United States)

    García-Tecedor, M.; Maestre, D.; Cremades, A.; Piqueras, J.

    2017-10-01

    Optical resonances are effectively tailored by engineering size, morphology and doping in tin oxide microstructures. The use of Cr shifts the light confinement to the near-infrared region, as compared to the undoped microstructures, while achieving good Q and F factors. Other issues, such as appropriate thickness to width ratio, allow the selection of Fabry–Pérot or Whispering Gallery modes, or the appearance of a combination of both kinds of resonances in the same microstructure. Morphology variability would contribute with flexibility in the design of systems for different applications, while combining the observed waveguiding behavior with the optical resonances in the same material is an advantage for applications based in a monolithic design. Refraction index of Cr doped tin oxide has been obtained.

  9. Experiments on Deflecting & Oscillating Waterjet

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    A new type jet,the oscillating & deflecting jet ,is put forward and its oscillating and deflecting characteristics are investigated.The nozzle of the self-oscillating & deflecting water jet consists of an upstream nozzle,a downstream nozzle,an oscillating chamber and two switches,It is experimentally shown that the deflective angle may reach 9.53 degeree,the generated pressure fluctuation is very regular and the jet can efficiently increase the ability for bradking and cutting by eliminating the water cushion effect associated with a continuous jet.

  10. Observation of green lasing at 537 nm from Er-ions by coupled photon-atom modes in a random cavity

    Science.gov (United States)

    Pham, Van Hoi; Do, Thuy Chi; Bui, Huy; Nguyen, The Anh; Van Nguyen, Thuy

    2011-03-01

    We present new results of a laser phenomenon that gives rise to a narrow green emission mode in a random photonic-crystal cavity based on an Er-doped glass-air gap-polymer with a 976 nm diode laser pump. Lasing occurs at 537 nm, which does not respond to the resonant radiative transition 2H11/2→4I15/2 4S3/2→4I15/2 in Erbium ions. This effect can be seen as photon-atom coupling in the context of the interaction between a single atom and/or a few atoms and resonant optical media, such as cavities or photonic crystals. Experimental results show that the random lasing mode directly originates from the coupled photon-atom mode inside the random cavity. The measured Q-factor is of 2100-2800 for a random cavity with an air gap of 600-1700 nm between Er-doped glass fiber and a coated polymer layer.

  11. HOM damping and multipacting analysis of the quarter-wave crab cavity

    Energy Technology Data Exchange (ETDEWEB)

    Wu Q.; Belomestnykh, S.; Ben-Zvi, I.; Calaga, R.

    2012-05-20

    The quarter-wave crab cavity design has been analyzed further to accommodate LHC requirements. The goal for the design is to provide strong deflecting voltage to the proton bunches at the IP, while keeping the effective length as short as possible. We will evaluate the higher order mode damping with two or four magnetic coupling dampers installed in different configuration. In this paper, we also show possible multipacting locations which are simulated by 2D and 3D codes.

  12. Electric Deflection of Rotating Molecules

    CERN Document Server

    Gershnabel, E

    2010-01-01

    We provide a theory of the deflection of polar and non-polar rotating molecules by inhomogeneous static electric field. Rainbow-like features in the angular distribution of the scattered molecules are analyzed in detail. Furthermore, we demonstrate that one may efficiently control the deflection process with the help of short and strong femtosecond laser pulses. In particular the deflection process may by turned-off by a proper excitation, and the angular dispersion of the deflected molecules can be substantially reduced. We study the problem both classically and quantum mechanically, taking into account the effects of strong deflecting field on the molecular rotations. In both treatments we arrive at the same conclusions. The suggested control scheme paves the way for many applications involving molecular focusing, guiding, and trapping by inhomogeneous fields.

  13. Narrow linewidth comb realized with a mode-locked fiber laser using an intra-cavity waveguide electro-optic modulator for high-speed control.

    Science.gov (United States)

    Iwakuni, Kana; Inaba, Hajime; Nakajima, Yoshiaki; Kobayashi, Takumi; Hosaka, Kazumoto; Onae, Atsushi; Hong, Feng-Lei

    2012-06-18

    We have developed an optical frequency comb using a mode-locked fiber ring laser with an intra-cavity waveguide electro-optic modulator controlling the optical length in the laser cavity. The mode-locking is achieved with a simple ring configuration and a nonlinear polarization rotation mechanism. The beat note between the laser and a reference laser and the carrier envelope offset frequency of the comb were simultaneously phase locked with servo bandwidths of 1.3 MHz and 900 kHz, respectively. We observed an out-of-loop beat between two identical combs, and obtained a coherent δ-function peak with a signal to noise ratio of 70 dB/Hz.

  14. Numerical modeling of the phase-conjugate laser with an intra-cavity stimulated Brillouin scattering mirror: Q-switching mode

    Science.gov (United States)

    Yashkir, Yuri

    2006-04-01

    We present a new computer numerical model of the phase-conjugate laser, utilizing an intra-cavity Stimulated Brillouin Scattering (SBS) element. The modelled laser system includes the active laser crystal which is placed between the output coupler mirror and a stimulated Brillouin scattering cell. The numerical model includes a set of rate equations for the active crystal inverse population, and for the photon density inside the laser cavity. The SBS backscattering model is based on a reduced set of coupled equations for electromagnetic fields for two waves (a pump wave and an SBS wave) propagating in opposite directions. The numerical integration of the set of equations simulates in detail the temporal dynamics of the laser. A wide range of realistic system parameters was numerically investigated. Different laser regimes (from a quasi -CW mode to a Q-switched mode) were numerically tested. The method of numerical modelling of such laser system can be efficiently used for an optimal laser design.

  15. Theoretical Analysis of Dependence of Nonlinear Effects in Mode-Locked Yb:YAG Lasers with a Highly Nonlinear Intra-Cavity Medium

    Directory of Open Access Journals (Sweden)

    Takeshi Yoshida

    2015-11-01

    Full Text Available Nonlinear ultrashort pulse propagation in a mode-locked Yb:YAG laser with a highly nonlinear intra-cavity medium is analyzed using a nonlinear Schrodinger equation. The output spectra are extended by the increased laser intensity, and spectral bandwidths wider than those of the gain medium are achieved. Moreover, pulse widths are shortened by increased laser intensity to considerably less than those of the gain medium. The simulation results qualitatively agree with the experimental results.

  16. Investigation of the resonance frequency and performance of a partially plasma filled reconfigurable cylindrical TE111 mode cavity

    Science.gov (United States)

    Hadaegh, Mostafa; Mohajeri, Farzad

    2017-05-01

    A partially plasma filled reconfigurable cylindrical cavity is proposed. Plasma offers an encouraging alternative to metal for a wide variety of microwave engineering applications. Implementation of a low-cost plasma element permits the resonant frequency to be changed electrically. The level of the resonant frequency shifts toward the empty-cavity resonant frequency and depends on certain parameters, such as the plasma diameter, relative permittivity and thickness of the plasma tube. In this article, we first introduce the partially plasma filled reconfigurable cylindrical cavity; then, the resonant frequency equation of the cavity is obtained by variational methods. Finally, we plot the resonant frequency versus different parameters of the cavity, which we compare with the results of the CST software. We show that the two results are compatible with each other.

  17. Generation of Picosecond X-Ray Pulses in the ALS Using RF Orbit Deflection

    CERN Document Server

    Robin, David; Fischer, Peter; Heimann, Philip; Kim, Dong-Hyun; Kwiatkowski, Slawomir; Li, Derun; Sannibale, Fernando; Steier, Christoph; Wan, Weishi; Wittmer, Walter; Zholents, Alexander

    2005-01-01

    A scheme is studied for producing ps length pulses of x-ray radiation from the Advanced Light Source (ALS) using two RF deflecting cavities. The cavities create vertical displacements of electrons correlated with their longitudinal position in the bunch. The two cavities separated by 180 degrees of vertical phase advance. This allows the vertical kick from one cavity to be compensated by the vertical kick of the other. The location of the cavities corresponds to the end of one straight section and the beginning of the following straight section. Halfway between the cavities a bending magnet source is located. The radiation from the bend can be compressed to ~1 ps in duration.

  18. Cavity-enhanced optical detection of carbon nanotube Brownian motion

    CERN Document Server

    Stapfner, S; Hunger, D; Weig, E M; Reichel, J; Favero, I

    2012-01-01

    Optical cavities with small mode volume are well-suited to detect the vibration of sub-wavelength sized objects. Here we employ a fiber-based, high-finesse optical microcavity to detect the Brownian motion of a freely suspended carbon nanotube at room temperature under vacuum. The optical detection resolves deflections of the oscillating tube down to 50pm/Hz^1/2. A full vibrational spectrum of the carbon nanotube is obtained and confirmed by characterization of the same device in a scanning electron microscope. Our work successfully extends the principles of high-sensitivity optomechanical detection to molecular scale nanomechanical systems.

  19. FPC and Hi-Pass Filter HOM Coupler Design for the RF Dipole Crab Cavity for the LHC HiLumi Upgrade

    CERN Document Server

    Li, Z; Delayen, Jean Roger; De Silva, S U; Park, HyeKyoung; Olave, R G

    2015-01-01

    A 400-MHz compact RF dipole (RFD) crab cavity design was jointly developed by Old Dominion University and SLAC under the support of US LARP program for the LHC HiLumi upgrade. The RFD cavity design is consisted of a rounded-square tank and two ridged deflecting poles, operating with a TE11-like dipole mode, which is the lowest mode of the cavity. A prototype RFD cavity is being manufactured and will be tested on the SPS beam line at CERN. The coaxial fundamental Power Coupler (FPC) of the prototype cavity was re-optimized to minimizing the power heating on the coupler internal antenna. A hi-pass filter HOM damping coupler was developed to achieve the required wakefield damping while maintaining a compact size to fit into the beam line space. In this paper, we will discuss the details of the RF optimization and tolerance analyses of the FPC and HOM couplers.

  20. Dynamics of 1.55 μm Wavelength Single-Mode Vertical-Cavity Surface-Emitting Laser Output under External Optical Injection

    Directory of Open Access Journals (Sweden)

    Kyong Hon Kim

    2012-01-01

    Full Text Available We review the temporal dynamics of the laser output spectrum and polarization state of 1.55 μm wavelength single-mode (SM vertical-cavity surface-emitting lasers (VCSELs induced by external optical beam injection. Injection of an external continuous-wave laser beam to a gain-switched SM VCSEL near the resonance wavelength corresponding to its main polarization-mode output was critical for improvement of its laser pulse generation characteristics, such as pulse timing-jitter reduction, linewidth narrowing, pulse amplitude enhancement, and pulse width shortening. Pulse injection of pulse width shorter than the cavity photon lifetime into the SM VCSEL in the orthogonal polarization direction with respect to its main polarization mode caused temporal delay of the polarization recovery after polarization switching (PS, and its delay was found to be the minimum at an optimized bias current. Polarization-mode bistability was observed even in the laser output of an SM VCSEL of a standard circularly cylindrical shape and used for all-optical flip-flop operations with set and reset injection pulses of very low pulse energy of order of the 3.5~4.5 fJ.

  1. Inherent calibration of a blue LED-CE-DOAS instrument to measure iodine oxide, glyoxal, methyl glyoxal, nitrogen dioxide, water vapour and aerosol extinction in open cavity mode

    Directory of Open Access Journals (Sweden)

    R. Thalman

    2010-12-01

    Full Text Available The combination of Cavity Enhanced Absorption Spectroscopy (CEAS with broad-band light sources (e.g. Light-Emitting Diodes, LEDs lends itself to the application of cavity enhanced Differential Optical Absorption Spectroscopy (CE-DOAS to perform sensitive and selective point measurements of multiple trace gases and aerosol extinction with a single instrument. In contrast to other broad-band CEAS techniques, CE-DOAS relies only on the measurement of relative intensity changes, i.e. does not require knowledge of the light intensity in the absence of trace gases and aerosols (I0. We have built a prototype LED-CE-DOAS instrument in the blue spectral range (420–490 nm to measure nitrogen dioxide (NO2, glyoxal (CHOCHO, methyl glyoxal (CH3COCHO, iodine oxide (IO, water vapour (H2O and oxygen dimers (O4. We demonstrate the first direct detection of methyl glyoxal, and the first CE-DOAS detection of CHOCHO and IO. The instrument is further inherently calibrated for light extinction from the cavity by observing O4 or H2O (at 477 nm and 443 nm and measuring the pressure, relative humidity and temperature independently. This approach is demonstrated by experiments where laboratory aerosols of known size and refractive index were generated and their extinction measured. The measured extinctions were then compared to the theoretical extinctions calculated using Mie theory (3–7 × 10−7cm−1. Excellent agreement is found from both the O4 and H2O retrievals. This enables the first inherently calibrated CEAS measurement at blue wavelengths in open cavity mode, and eliminates the need for sampling lines to supply air to the cavity, i.e., keep the cavity enclosed and/or aerosol free. Measurements in open cavity mode are demonstrated for CHOCHO, CH3COCHO, NO2, H2O and aerosol extinction. Our prototype

  2. Inherent calibration of a novel LED-CE-DOAS instrument to measure iodine oxide, glyoxal, methyl glyoxal, nitrogen dioxide, water vapour and aerosol extinction in open cavity mode

    Science.gov (United States)

    Thalman, R.; Volkamer, R.

    2010-06-01

    The combination of Cavity Enhanced Absorption Spectroscopy (CEAS) with broad-band light sources (e.g. Light-Emitting Diodes, LEDs) lends itself to the application of cavity enhanced Differential Optical Absorption Spectroscopy (CE-DOAS) to perform sensitive and selective point measurements of multiple trace gases and aerosol extinction with a single instrument. In contrast to other broad-band CEAS techniques, CE-DOAS relies only on the measurement of relative intensity changes, i.e. does not require knowledge of the light intensity in the absence of trace gases and aerosols (I0). We have built a prototype LED-CE-DOAS instrument in the blue spectral range (420-490 nm) to measure nitrogen dioxide (NO2), glyoxal (CHOCHO), methyl glyoxal (CH3COCHO), iodine oxide (IO), water vapour (H2O) and oxygen dimers (O4). We demonstrate the first CEAS detection of methyl glyoxal, and the first CE-DOAS detection of CHOCHO and IO. A further innovation consists in the measurement of extinction losses from the cavity, e.g. due to aerosols, at two wavelengths by observing O4 (477 nm) and H2O (443 nm) and measuring the pressure, relative humidity and temperature independently. This approach is demonstrated by experiments where laboratory aerosols of known size and refractive index were generated and their extinction measured. The measured extinctions were then compared to the theoretical extinctions calculated using Mie theory (3-7×10-7 cm-1). Excellent agreement is found from both the O4 and H2O retrievals. This enables the first inherently calibrated CEAS measurement in open cavity mode (mirrors facing the open atmosphere), and eliminates the need for sampling lines to supply air to the cavity, and/or keep the cavity enclosed and aerosol free. Measurements in open cavity mode are demonstrated for CHOCHO, CH3COCHO, NO2, H2O and aerosol extinction at 477 nm and 443 nm. Our prototype LED-CE-DOAS provides a low cost, yet research grade innovative instrument for applications in simulation

  3. Inherent calibration of a novel LED-CE-DOAS instrument to measure iodine oxide, glyoxal, methyl glyoxal, nitrogen dioxide, water vapour and aerosol extinction in open cavity mode

    Directory of Open Access Journals (Sweden)

    R. Thalman

    2010-06-01

    Full Text Available The combination of Cavity Enhanced Absorption Spectroscopy (CEAS with broad-band light sources (e.g. Light-Emitting Diodes, LEDs lends itself to the application of cavity enhanced Differential Optical Absorption Spectroscopy (CE-DOAS to perform sensitive and selective point measurements of multiple trace gases and aerosol extinction with a single instrument. In contrast to other broad-band CEAS techniques, CE-DOAS relies only on the measurement of relative intensity changes, i.e. does not require knowledge of the light intensity in the absence of trace gases and aerosols (I0. We have built a prototype LED-CE-DOAS instrument in the blue spectral range (420–490 nm to measure nitrogen dioxide (NO2, glyoxal (CHOCHO, methyl glyoxal (CH3COCHO, iodine oxide (IO, water vapour (H2O and oxygen dimers (O4. We demonstrate the first CEAS detection of methyl glyoxal, and the first CE-DOAS detection of CHOCHO and IO. A further innovation consists in the measurement of extinction losses from the cavity, e.g. due to aerosols, at two wavelengths by observing O4 (477 nm and H2O (443 nm and measuring the pressure, relative humidity and temperature independently. This approach is demonstrated by experiments where laboratory aerosols of known size and refractive index were generated and their extinction measured. The measured extinctions were then compared to the theoretical extinctions calculated using Mie theory (3–7×10-7 cm-1. Excellent agreement is found from both the O4 and H2O retrievals. This enables the first inherently calibrated CEAS measurement in open cavity mode (mirrors facing the open atmosphere, and eliminates the need for sampling lines to supply air to the cavity, and/or keep the cavity enclosed and aerosol free. Measurements in open cavity mode are demonstrated for CHOCHO, CH3COCHO, NO2, H2

  4. Inherent calibration of a blue LED-CE-DOAS instrument to measure iodine oxide, glyoxal, methyl glyoxal, nitrogen dioxide, water vapour and aerosol extinction in open cavity mode

    Science.gov (United States)

    Thalman, R.; Volkamer, R.

    2010-12-01

    The combination of Cavity Enhanced Absorption Spectroscopy (CEAS) with broad-band light sources (e.g. Light-Emitting Diodes, LEDs) lends itself to the application of cavity enhanced Differential Optical Absorption Spectroscopy (CE-DOAS) to perform sensitive and selective point measurements of multiple trace gases and aerosol extinction with a single instrument. In contrast to other broad-band CEAS techniques, CE-DOAS relies only on the measurement of relative intensity changes, i.e. does not require knowledge of the light intensity in the absence of trace gases and aerosols (I0). We have built a prototype LED-CE-DOAS instrument in the blue spectral range (420-490 nm) to measure nitrogen dioxide (NO2), glyoxal (CHOCHO), methyl glyoxal (CH3COCHO), iodine oxide (IO), water vapour (H2O) and oxygen dimers (O4). We demonstrate the first direct detection of methyl glyoxal, and the first CE-DOAS detection of CHOCHO and IO. The instrument is further inherently calibrated for light extinction from the cavity by observing O4 or H2O (at 477 nm and 443 nm) and measuring the pressure, relative humidity and temperature independently. This approach is demonstrated by experiments where laboratory aerosols of known size and refractive index were generated and their extinction measured. The measured extinctions were then compared to the theoretical extinctions calculated using Mie theory (3-7 × 10-7cm-1). Excellent agreement is found from both the O4 and H2O retrievals. This enables the first inherently calibrated CEAS measurement at blue wavelengths in open cavity mode, and eliminates the need for sampling lines to supply air to the cavity, i.e., keep the cavity enclosed and/or aerosol free. Measurements in open cavity mode are demonstrated for CHOCHO, CH3COCHO, NO2, H2O and aerosol extinction. Our prototype LED-CE-DOAS provides a low cost, yet research grade innovative instrument for applications in simulation chambers and in the open atmosphere.

  5. Opto-mechanical design of a buckling cavity in a novel high-performance outside-plant robust field installable single-mode fibre connector

    Science.gov (United States)

    Ebraert, Evert; Van Erps, Jürgen; Beri, Stefano; Watté, Jan; Thienpont, Hugo

    2014-05-01

    Fibre-to-the-home (FTTH) networks provide an ideal means to reach the goal the European Union has set to provide 50 % of the households with a broadband connection faster than 100 Mb/s. Deployment of FTTH networks, which is still costly today, could be significantly boosted by novel ferrule-less connectors which don't require highly skilled personnel and allow installation in the field. We propose a ferrule-less connector in which two single-mode fibres (SMFs) are aligned and maintain physical contact by ensuring that at least one fibre is in a buckled state. To this end, we design a cavity in which a fibre can buckle in a controlled way. Using finite element analysis simulations to investigate the shape of the formed buckle for various buckling cavity lengths, we show that it can be accurately approximated by a cosine function. In addition, the optical performance of a buckled SMF is investigated by bending loss calculations and simulations. We show a good agreement between the analytical and the simulated bending loss results for a G.652 fibre at a wavelength of 1550 nm. Buckling cavity lengths smaller than 20 mm should be avoided to keep the optical bending loss due to buckling below 0.1 dB. In this case the cavity height should at least be 2 mm to avoid mechanical confinement of the fibre.

  6. Multipacting Analysis of the Superconducting Parallel-bar Cavity

    Energy Technology Data Exchange (ETDEWEB)

    S.U. De Silva, J.R. Delayen,

    2011-03-01

    The superconducting parallel-bar cavity is a deflecting/crabbing cavity with attractive properties, compared to other conventional designs, that is being considered for a number of applications. Multipacting can be a limiting factor to the performance of in any superconducting structure. In the parallel-bar cavity the main contribution to the deflection is due to the transverse deflecting voltage, between the parallel bars, making the design potentially prone to multipacting. This paper presents the results of analytical calculations and numerical simulations of multipacting in the parallel-bar cavity with resonant voltage, impact energies and corresponding particle trajectories.

  7. Cavity spatial mode-locking and high controllability of radial output coupling for circular/square plasmonic nano-resonator lasers.

    Science.gov (United States)

    Chen, Xi; Huang, Yingyan; Ho, Seng-Tiong

    2015-02-01

    We proposed and investigated a novel output coupling scheme for a circular and a square plasmonic nano-ring laser based on a T-shaped radial coupler that is easier to realize than a tangential coupler. The amount of coupling efficiency is shown to be highly controllable from a few percent to tens of percents. This is due to the fact that the standing-wave lasing mode pattern will rotate to give the minimal cavity loss at the T-coupler's location, making the amount of output coupling surprisingly low and hence, controllable. For a non-circular cavity, other symmetry-breaking and geometry-induced scattering could result in separate mode-pattern locking. These give a few main ways to control and optimize the coupling efficiency: via widening/narrowing or rotating the T-coupler's waveguide, or, for the case of a non-circular cavity, via shifting the location of the T-coupler. We observed increased unidirectional lasing induced by either rotating the waveguide or shifting it (for non-circular cases). We simulated the coupling using Maxwell's equations based on the multi-level multi-electron FDTD (MLME-FDTD) method to realistically model the lasing and output coupling behaviors of such plasmonic semiconductor lasers.

  8. Gain-switching dynamics in optically pumped single-mode InGaN vertical-cavity surface-emitting lasers.

    Science.gov (United States)

    Chen, Shaoqiang; Asahara, Akifumi; Ito, Takashi; Zhang, Jiangyong; Zhang, Baoping; Suemoto, Tohru; Yoshita, Masahiro; Akiyama, Hidefumi

    2014-02-24

    The gain-switching dynamics of single-mode pulses were studied in blue InGaN multiple-quantum-well vertical-cavity surface-emitting lasers (VCSELs) through impulsive optical pumping. We measured the shortest single-mode pulses of 6.0 ps in width with a method of up-conversion, and also obtained the pulse width and the delay time as functions of pump powers from streak-camera measurements. Single-mode rate-equation calculations quantitatively and consistently explained the observed data. The calculations indicated that the pulse width in the present VCSELs was mostly limited by modal gain, and suggested that subpicosecond pulses should be possible within feasible device parameters.

  9. 5.5 W continuous-wave TEM00-mode Nd:YAG solar laser by a light-guide/2V-shaped pump cavity

    Science.gov (United States)

    Almeida, J.; Liang, D.; Vistas, C. R.; Bouadjemine, R.; Guillot, E.

    2015-12-01

    A significant progress in TEM00-mode solar laser power and efficiency with heliostat-parabolic mirror system is reported here. A double-stage light-guide/2V-shaped pump cavity is used to efficiently couple and redistribute the concentrated pump light from a 2-m-diameter parabolic mirror to a 4-mm-diameter, 30-mm-length, 1.1 at.% Nd:YAG single-crystal rod. The light guide with large rectangular cross section enables a stable uniform pumping profile along the laser rod, resulting also in an enhanced tracking error compensation capacity. 5.5 W cw TEM00-mode solar laser power was measured at the output of a thermally near unstable asymmetric resonator. 150 and 157 % improvement in TEM00-mode solar laser collection efficiency and slope efficiency were obtained, respectively.

  10. Effect of Surface Plasmon Coupling to Optical Cavity Modes on the Field Enhancement and Spectral Response of Dimer-Based sensors

    KAUST Repository

    Alrasheed, Salma

    2017-09-05

    We present a theoretical approach to narrow the plasmon linewidth and enhance the near-field intensity at a plasmonic dimer gap (hot spot) through coupling the electric localized surface plasmon (LSP) resonance of a silver hemispherical dimer with the resonant modes of a Fabry-Perot (FP) cavity. The strong coupling is demonstrated by the large anticrossing in the reflection spectra and a Rabi splitting of 76 meV. Up to 2-fold enhancement increase can be achieved compared to that without using the cavity. Such high field enhancement has potential applications in optics, including sensors and high resolution imaging devices. In addition, the resonance splitting allows for greater flexibility in using the same array at different wavelengths. We then further propose a practical design to realize such a device and include dimers of different shapes and materials.

  11. HF power couplers for pulsed superconducting cavity resonators; Coupleurs de puissance HF pour cavites supraconductrices en mode pulse

    Energy Technology Data Exchange (ETDEWEB)

    Jenhani, Hassen [Laboratoire de l' Accelerateur Lineaire, IN2P3-CNRS et Universite de Paris-Sud, BP 34, F-91898 Orsay Cedex (France)

    2006-11-15

    Recent years have seen an impressive improvement in the accelerating gradients obtained in superconducting cavities. Consequently, such cavities have become attractive candidates for large superconducting linear accelerator projects such as the European XFEL and the International Linear Collider (ILC). As a result, there is a strong interest in reducing RF conditioning time and improving the performance of the input power couplers for these cavities. The so-called TTF-III input power coupler, adopted for the XFEL superconducting RF cavities are complex components. In order to better understand the behavior of this component we have performed a series of experiments on a number of such couplers. Initially, we developed a fully automated RF high power test stand for coupler conditioning procedure. Following this, we performed a series of coupler conditioning tests. This has allowed the study of the coupler behavior during processing. A number of experiments were carried out to evaluate the in-situ baking effect on the conditioning time. Some of the conditioned couplers were sent to DESY in order to be tested on 9-cells TESLA cavities under cryogenic conditions. These tests have shown that the couplers in no way limit the cavity performance, even up to gradients of 35 MV/m. The main objective of our coupler studies was the reduction of their conditioning time, which represents one of the most important criteria in the choice of coupler for high energy linacs. Excellent progress in reducing the conditioning time has been demonstrated by making appropriate modifications to the conditioning procedure. Furthermore, special attention was paid to electron generation processes in the couplers, via multipacting. Simulations of this process were made on both the TTF-III coupler and on a new coupler prototype, TTF-V. Experiments aimed at suppressing multipacting were also successfully achieved by using a DC bias on the inner conductor of the co-axial coupler. (author)

  12. Collapse-revival in entanglement and photon statistics: the interaction of a three-level atom with a two-mode quantized field in cavity optomechanics

    Science.gov (United States)

    Hassani Nadiki, M.; Tavassoly, M. K.

    2016-12-01

    In this paper the interaction of a three-level atom in V-configuration with a two-mode quantized field in cavity optomechanics is studied. To achieve the purpose, we first deduce the effective Hamiltonian and evaluate the explicit time-dependent form of the state vector of the whole system by choosing special initial conditions for atom, field and the oscillatory mirror. Interestingly, we can obtain the time evolution of atomic linear entropy, population inversion, quantum statistics and squeezing, both analytically and numerically. The results show that the entanglement between the atom and the subsystem of field and mirror, and all above-mentioned physical quantities can be appropriately controlled by the initial atom-field state condition, the parameters of cavity optomechanics as well as atom-field coupling strengths. In particular, the appearance of collapse-revival phenomenon in the entanglement and quantum photon statistics, also the full sub-Poissonian statistics in the two modes of field as well as in the mechanical mode of optomechanical system are noticeable features of the work.

  13. Benchmarking Asteroid-Deflection Experiment

    Science.gov (United States)

    Remington, Tane; Bruck Syal, Megan; Owen, John Michael; Miller, Paul L.

    2016-10-01

    An asteroid impacting Earth could have devastating consequences. In preparation to deflect or disrupt one before it reaches Earth, it is imperative to have modeling capabilities that adequately simulate the deflection actions. Code validation is key to ensuring full confidence in simulation results used in an asteroid-mitigation plan. We are benchmarking well-known impact experiments using Spheral, an adaptive smoothed-particle hydrodynamics code, to validate our modeling of asteroid deflection. We describe our simulation results, compare them with experimental data, and discuss what we have learned from our work. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. LLNL-ABS-695540

  14. Geometric formula for prism deflection

    Indian Academy of Sciences (India)

    Apoorva G Wagh; Veer Chand Rakhecha

    2004-08-01

    While studying neutron deflections produced by a magnetic prism, we have stumbled upon a simple `geometric' formula. For a prism of refractive index close to unity, the deflection simply equals the product of the refractive power − 1 and the base-to-height ratio of the prism, regardless of the apex angle. The base and height of the prism are measured respectively along and perpendicular to the direction of beam propagation within the prism. The geometric formula greatly simplifies the optimisation of prism parameters to suit any specific experiment.

  15. Relativistic Stern-Gerlach Deflection

    CERN Document Server

    Talman, Richard

    2016-01-01

    Modern advances in polarized beam control should make it possible to accurately measure Stern-Gerlach (S-G) deflection of relativistic beams. Toward this end a relativistically covariant S-G formalism is developed that respects the opposite behavior under inversion of electric and magnetic fields. Not at all radical, or even new, this introduces a distinction between electric and magnetic fields that is not otherwise present in pure Maxwell theory. Experimental configurations (mainly using polarized electron beams passing through magnetic or electric quadrupoles) are described. Electron beam preparation and experimental methods needed to detect the extremely small deflections are discussed.

  16. Statistical methods for transverse beam position diagnostics with higher order modes in third harmonic 3.9 GHz superconducting accelerating cavities at FLASH

    CERN Document Server

    Zhang, P; Jones, R M

    2014-01-01

    Beam-excited higher order modes (HOM) can be used to provide beam diagnostics. Here we focus on 3.9 GHz superconducting accelerating cavities. In particular we study dipole mode excitation and its application to beam position determinations. In order to extract beam position information, linear regression can be used. Due to a large number of sampling points in the waveforms, statistical methods are used to effectively reduce the dimension of the system, such as singular value decomposition (SVD) and k-means clustering. These are compared with the direct linear regression (DLR) on the entire waveforms. A cross-validation technique is used to study the sample independent precisions of the position predictions given by these three methods. A RMS prediction error in the beam position of approximately 50 micron can be achieved by DLR and SVD, while k-means clustering suggests 70 micron.

  17. 10 kHz ps 1342 nm laser generation by an electro-optically cavity-dumped mode-locked Nd:YVO4 laser

    Science.gov (United States)

    Chen, Ying; Liu, Ke; He, Li-jiao; Yang, Jing; Zong, Nan; Yang, Feng; Gao, Hong-wei; Liu, Zhao; Yuan, Lei; Lan, Ying-jie; Bo, Yong; Peng, Qin-jun; Cui, Da-fu; Xu, Zu-yan

    2017-01-01

    We have demonstrated an electro-optically cavity-dumped mode-locked (CDML) picosecond Nd:YVO4 laser at 1342 nm with 880 nm diode-laser direct pumping. At a repetition rate of 10 kHz, an average output power of 0.119 W was achieved, corresponding to a pulse energy of 11.9 μJ. Compared with the continuous wave mode-locking pulse energy of 17.5 nJ, the CDML pulse energy was 680 times higher. The pulse width was measured to be 33.4 ps, resulting in the peak power of 356 kW. Meanwhile, the beam quality was nearly diffraction limited with an average beam quality factor M2 of 1.29.

  18. Implementation of Radio-Frequency Deflecting Devices for Comprehensive High-Energy Electron Beam Diagnosis

    Science.gov (United States)

    Craievich, Paolo; Petronio, Marco; Biedron, Sandra G.; Castronovo, Davide; Dal Forno, Massimo; Di Mitri, Simone; Faure, Nicolas; La Civita, Daniele; Penco, Giuseppe; Rumiz, Luca; Sturari, Luca; Vescovo, Roberto; Wang, Defa

    2015-02-01

    In next-generation light sources, high-brightness electron beams are used in a free-electron laser configuration to produce light for use by scientists and engineers in numerous fields of research. High-brightness beams are described for such light sources as having low transverse and longitudinal emittances, high peak currents, and low slice emittance and energy spread. The optimal generation and preservation of such high-brightness electron beams during the acceleration process and propagation to and through the photon-producing element is imperative to the quality and performance of the light source. To understand the electron beam's phase space in the accelerating section of a next-generation light source machine, we employed radio-frequency cavities operating in a deflecting mode in conjunction with a magnetic spectrometer and imaging system for both low (250 MeV) and high (1.2 GeV) electron energies. This high-resolution, high-energy system is an essential diagnostic for the optimization and control of the electron beam in the FERMI light source generating fully transversely and longitudinally coherent light in the VUV to soft x-ray wavelength regimes. This device is located at the end of the linear accelerator in order to provide the longitudinal phase space nearest to the entrance of the photon-producing beam-lines. Here, we describe the design, fabrication, characterization, commissioning, and operational implementation of this transverse deflecting cavity structure diagnostic system for the high-energy (1.2 GeV) regime.

  19. Linewidth broadening and emission saturation of a resonantly excited quantum dot monitored via an off-resonant cavity mode

    DEFF Research Database (Denmark)

    Ulhaq, A.; Ates, Serkan; Weiler, S.;

    2010-01-01

    We report on the robustness of a detuned mode channel for reading out the relevant s-shell properties of a resonantly excited coupled quantum dot (QD) in a pillar microcavity. The line broadening of the QD s-shell is “monitored” by the mode signal with high conformity to the directly measured QD ...

  20. General expressions for the coupling coefficient, quality and filling factors for a cavity with an insert using energy coupled mode theory.

    Science.gov (United States)

    Elnaggar, Sameh Y; Tervo, Richard; Mattar, Saba M

    2014-05-01

    A cavity (CV) with a dielectric resonator (DR) insert forms an excellent probe for the use in electron paramagnetic resonance (EPR) spectrometers. The probe's coupling coefficient, κ, the quality factor, Q, and the filling factor, η are vital in assessing the EPR spectrometer's performance. Coupled mode theory (CMT) is used to derive general expressions for these parameters. For large permittivity the dominating factor in κ is the ratio of the DR and CV cross sectional areas rather than the dielectric constant. Thus in some cases, resonators with low dielectric constant can couple much stronger with the cavity than do resonators with a high dielectric constant. When the DR and CV frequencies are degenerate, the coupled η is the average of the two uncoupled ones. In practical EPR probes the coupled η is approximately half of that of the DR. The Q of the coupled system generally depends on the eigenvectors, uncoupled frequencies (ω1,ω2) and the individual quality factors (Q1,Q2). It is calculated for different probe configurations and found to agree with the corresponding HFSS® simulations. Provided there is a large difference between the Q1, Q2 pair and the frequencies of DR and CV are degenerate, Q is approximately equal to double the minimum of Q1 and Q2. In general, the signal enhancement ratio, Iwithinsert/Iempty, is obtained from Q and η. For low loss DRs it only depends on η1/η2. However, when the DR has a low Q, the uncoupled Qs are also needed. In EPR spectroscopy it is desirable to excite only a single mode. The separation between the modes, Φ, is calculated as a function of κ and Q. It is found to be significantly greater than five times the average bandwidth. Thus for practical probes, it is possible to excite one of the coupled modes without exciting the other. The CMT expressions derived in this article are quite general and are in excellent agreement with the lumped circuit approach and finite numerical simulations. Hence they can also be

  1. AIDA: Asteroid Impact & Deflection Assessment

    Science.gov (United States)

    Cheng, A. F.; Galvez, A.; Carnelli, I.; Michel, P.; Rivkin, A.; Reed, C.

    2012-12-01

    To protect the Earth from a hazardous asteroid impact, various mitigation methods have been proposed, including deflection of the asteroid by a spacecraft impact. AIDA, consisting of two mission elements, the Double Asteroid Redirection Test (DART) and the Asteroid Impact Monitoring (AIM) mission, is a demonstration of asteroid deflection. To date, there has been no such demonstration, and there is major uncertainty in the result of a spacecraft impact onto an asteroid, that is, the amount of deflection produced by a given momentum input from the impact. This uncertainty is in part due to unknown physical properties of the asteroid surface, such as porosity and strength, and in part due to poorly understood impact physics such that the momentum carried off by ejecta is highly uncertain. A first mission to demonstrate asteroid deflection would not only be a major step towards gaining the capability to mitigate an asteroid hazard, but in addition it would return unique information on an asteroid's strength, other surface properties, and internal structure. This information return would be highly relevant to future human exploration of asteroids. We report initial results of the AIDA joint mission concept study undertaken by the Johns Hopkins Applied Physics Laboratory and ESA with support from NASA centers including Goddard, Johnson and Jet Propulsion Laboratory. For AIDA, the DART spacecraft impactor study is coordinated with an ESA study of the AIM mission, which would rendezvous with the same asteroid to measure effects of the impact. Unlike the previous Don Quijote mission study performed by ESA in 2005-2007, DART envisions an impactor spacecraft to intercept the secondary member of a binary near-Earth asteroid. DART includes ground-based observations to measure the deflection independently of the rendezvous spacecraft observations from AIM, which also measures deflection and provides detailed characterization of the target asteroid. The joint mission AIDA

  2. Coupled resonator vertical cavity laser

    Energy Technology Data Exchange (ETDEWEB)

    Choquette, K.D.; Chow, W.W.; Hou, H.Q.; Geib, K.M.; Hammons, B.E.

    1998-01-01

    The monolithic integration of coupled resonators within a vertical cavity laser opens up new possibilities due to the unique ability to tailor the interaction between the cavities. The authors report the first electrically injected coupled resonator vertical-cavity laser diode and demonstrate novel characteristics arising from the cavity coupling, including methods for external modulation of the laser. A coupled mode theory is used model the output modulation of the coupled resonator vertical cavity laser.

  3. Nonclassical effects of a two-level spin system interacting with a two-mode cavity field via two-photon transition.

    Science.gov (United States)

    Grinberg, Horacio

    2008-12-18

    The interaction of a two-level cyclic XY n-spin model with a two-mode cavity field involving two-photon transitions is investigated through a generalized Jaynes-Cummings model in the rotating-wave approximation. The two-photon interacting Hamiltonian becomes from the replacement of each single-mode field in the one-photon interacting Hamiltonian with the second-harmonic generation. It was assumed that initially the correlated field modes are in disentangled coherent states having the same photon distribution and that the spin system is in an excited state. At any time t > 0, the spin system and the field are in an entangled state, in this case, via a unitary time evolution operator. Thus, the spontaneous decay of a spin level was treated by considering the interaction of the two-level spin system with the modes of the universe in the vacuum state. The different cases of interest, characterized in terms of a detuning parameter for each mode, which emerge from nonvanishing commutation relations, were analytically implemented and numerically discussed for various values of the initial mean photon number and spin-photon coupling constants. Photon distribution, time evolution of the spin population inversion, as well as the statistical properties of the field leading to the possible production of nonclassical states, such as antibunched light, violations of the Cauchy-Schwartz inequality, and second- and fourth-order squeezing, are examined. The case of zero detuning of both modes was treated in terms of a linearization of the expansion of the time evolution operator, while in other three cases, the computations were conducted via second- and third-order Dyson perturbation expansion of the time evolution operator matrix elements for the excited and ground states of the spin system, respectively.

  4. Quantum-enhanced metrology with the single-mode coherent states of an optical cavity inside a quantum feedback loop

    Science.gov (United States)

    Clark, Lewis A.; Stokes, Adam; Beige, Almut

    2016-08-01

    In this paper, we use the nonlinear generator of dynamics of the individual quantum trajectories of an optical cavity inside an instantaneous quantum feedback loop to measure the phase shift between two pathways of light with a precision above the standard quantum limit. The feedback laser provides a reference frame and constantly increases the dependence of the state of the resonator on the unknown phase. Since our quantum metrology scheme can be implemented with current technology and does not require highly efficient single photon detectors, it should be of practical interest until highly entangled many-photon states become more readily available.

  5. Elevator deflections on the icing process

    Science.gov (United States)

    Britton, Randall K.

    1990-01-01

    The effect of elevator deflection of the horizontal stabilizer for certain icing parameters is investigated. Elevator deflection can severely change the lower and upper leading-edge impingement limits, and ice can accrete on the elevator itself. Also, elevator deflection had practically no effect on the maximum local collection efficiency. It is shown that for severe icing conditions (large water droplets), elevator deflections that increase the projected height of the airfoil can significantly increase the total collection efficiency of the airfoil.

  6. Strong mode coupling in InP quantum dot-based GaInP microdisk cavity dimers

    Science.gov (United States)

    Witzany, M.; Liu, T.-L.; Shim, J.-B.; Hargart, F.; Koroknay, E.; Schulz, W.-M.; Jetter, M.; Hu, E.; Wiersig, J.; Michler, P.

    2013-01-01

    We report on strong mode coupling in closely spaced GaInP microdisk dimer structures including InP quantum dots as the active medium. Using electron beam lithography and a combination of dry- and wet-etch processes, dimers with inter-disk separations down to d < 100 nm have been fabricated. Applying a photo-thermal heating scheme, we overcome the spectral mode detuning due to the size mismatch between the two disks forming the dimer. We observe signatures of mode coupling in the corresponding photoluminescence spectra with coupling energies of up to 0.66 MeV. With the aid of a numerical analysis, we specify the geometrical and physical factors of the microdisk dimer precisely, and reproduce its spectrum with good agreement.

  7. A resonance Raman enhancement mechanism for axial vibrational modes in the pyridine adduct of myoglobin proximal cavity mutant (H93G).

    Science.gov (United States)

    Franzen, Stefan; Brown, Derek; Gaff, John; Delley, B

    2012-09-06

    The proximal cavity mutant of myoglobin consists of a mutation of the proximal histidine to glycine (H93G), which permits exogenous ligands to bind to the heme iron. A non-native pyridine ligand can ligate to the heme to yield a five-coordinate adduct, H93G(Pyr), that cannot be formed freely in solution since the six-coordinate bis-pyridine adduct is more stable than the five-coordinate adduct. We have used resonance Raman spectroscopy in the Soret band region of the heme to study the enhancement of axial vibrations of bound pyridine in the H93G(Pyr) adduct. The observation that the pyridine ring breathing mode (ν(1)) and the symmetric ring stretching (ν(3)) modes are enhanced under these conditions is explained by a computational approach that shows that coupling of the π-system of the heme with the p-orbitals of the pyridine is analogous to π-backbonding in diatomic ligand adducts of heme proteins. The result has the broader significance that it suggests that the resonance enhancement of pyridine modes could be an important aspect of Raman scattering of pyridine on conducting surfaces such as those studied in surface enhanced Raman scattering experiments.

  8. Ultrafast and widely tuneable vertical-external-cavity surface-emitting laser, mode-locked by a graphene-integrated distributed Bragg reflector.

    Science.gov (United States)

    Zaugg, C A; Sun, Z; Wittwer, V J; Popa, D; Milana, S; Kulmala, T S; Sundaram, R S; Mangold, M; Sieber, O D; Golling, M; Lee, Y; Ahn, J H; Ferrari, A C; Keller, U

    2013-12-16

    We report a versatile way of controlling the unsaturated loss, modulation depth and saturation fluence of graphene-based saturable absorbers (GSAs), by changing the thickness of a spacer between a single layer graphene (SLG) and a high-reflection mirror. This allows us to modulate the electric field intensity enhancement at the GSA from 0 up to 400%, due to the interference of incident and reflected light at the mirror. The unsaturated loss of the SLG-mirror-assembly can be reduced to ∼0. We use this to mode-lock a vertical-external-cavity surface-emitting laser (VECSEL) from 935 to 981 nm. This approach can be applied to integrate SLG into various optical components, such as output coupler mirrors, dispersive mirrors or dielectric coatings on gain materials. Conversely, it can also be used to increase the absorption (up to 10%) in various graphene based photonics and optoelectronics devices, such as photodetectors.

  9. High power, widely tunable, mode-hop free, continuous wave external cavity quantum cascade laser for multi-species trace gas detection

    Energy Technology Data Exchange (ETDEWEB)

    Centeno, R.; Marchenko, D.; Mandon, J.; Cristescu, S. M.; Harren, F. J. M., E-mail: F.Harren@science.ru.nl [Life Science Trace Gas Facility, Molecular and Laser Physics, Institute for Molecules and Materials, Radboud University, P.O. Box 9010, NL-6500 GL Nijmegen (Netherlands); Wulterkens, G. [TechnoCentrum, Radboud University, Heyendaalseweg 135, 6525AJ Nijmegen (Netherlands)

    2014-12-29

    We present a high power, widely tunable, continuous wave external cavity quantum cascade laser designed for infrared vibrational spectroscopy of molecules exhibiting broadband and single line absorption features. The laser source exhibits single mode operation with a tunability up to 303 cm{sup −1} (∼24% of the center wavelength) at 8 μm, with a maximum optical output power of 200 mW. In combination with off-axis integrated output spectroscopy, trace-gas detection of broadband absorption gases such as acetone was performed and a noise equivalent absorption sensitivity of 3.7 × 10{sup −8 }cm{sup −1 }Hz{sup −1/2} was obtained.

  10. Frequency Up- and Down-conversions in Two-mode Cavity%两模腔中的参量上转换和下转换

    Institute of Scientific and Technical Information of China (English)

    李斌; 冯勋立; 张智明

    2011-01-01

    提出了一种通过建立双线性二次哈密顿量在量子腔中实现参量上转换和下转换的方案.通常在非线性过程中,介质本身不参与能量的净交换,但光波频率可以发生转换的作用称为参量转换作用.此方案建立在一个四能级原子同时与两经典场和两量子场相互作用的基础上,理论属于非线性光学四波混频范畴.将原子制备在合适的能级上,经典光场与相应的能级发生共振,而同时量子光场与相应的能级产生大失谐相互作用,在强相互作用区域内,原子和腔场失耦合,进而实现腔模的参量转换.根据所制备初始能级的不同以及光场激发能级的差异,分别实现了参量上转换和参量下转换.在利用参量下转换制备压缩算符后,对实验的可行性进行了讨论,并且给出了理论值.结果表明:在级联三能原子中采用一个级联双光子过程代替了原来的两个偶极禁戒跃迁间的经典驱动,可以保证高的不同频率之间的转换效率,并且用于光的量子操控和量子信息处理.%A scheme was proposed to construct bilinear and quadratic Hamiltonians for frequency up-and down-conversions in cavity quantum electrodynamics (QED).Generally,in nonlinear optics,the interaction that the energe swaps between different optic modes without atomic transition is named frequency conversion.The proposed scheme was based on the interactions of a single four-level atom simultaneously with two classical driving fields and a two-mode cavity field,which is in the domain of four-wave mixing.By initially preparing the atom in a suitable state,each pump light was resonant with its transition,and two quantum modes were large tune to the other two transition,respectively,In the strong laser regime,the atomic degrees of freedom could be decoupled from the cavity degrees of freedom and the frequency conversion could be realized for the cavity modes.Due to the different initial states and

  11. Dynamic neutronic and stability analysis of a burst mode, single cavity gas core reactor Brayton cycle space power system

    Science.gov (United States)

    Dugan, Edward T.; Kutikkad, Kiratadas

    The conceptual, burst-mode gaseous-core reactor (GCR) space nuclear power system presently subjected to reactor-dynamics and system stability studies operates on a closed Brayton cycle, via disk MHD generator for energy conversion. While the gaseous fuel density power coefficient of reactivity is found to be capable of rapidly stabilizing the GCR system, the power of this feedback renders standard external reactivity insertions inadequate for significant power-level changes during normal operation.

  12. A study of beam position diagnostics with beam-excited dipole higher order modes using a downconverter test electronics in third harmonic 3.9 GHz superconducting accelerating cavities at FLASH

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, P. [Manchester Univ. (United Kingdom); Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Baboi, N.; Lorbeer, B.; Wamsat, T. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Eddy, N.; Fellenz, B.; Wendt, M. [Fermi National Accelerator Lab., Batavia, IL (United States); Jones, R.M. [Manchester Univ. (United Kingdom); The Cockcroft Institute, Daresbury (United Kingdom)

    2012-08-15

    Beam-excited higher order modes (HOM) in accelerating cavities contain transverse beam position information. Previous studies have narrowed down three modal options for beam position diagnostics in the third harmonic 3.9 GHz cavities at FLASH. Localized modes in the beam pipes at approximately 4.1 GHz and in the fifth cavity dipole band at approximately 9 GHz were found, that can provide a local measurement of the beam position. In contrast, propagating modes in the first and second dipole bands between 4.2 and 5.5 GHz can reach a better resolution. All the options were assessed with a specially designed test electronics built by Fermilab. The aim is to de ne a mode or spectral region suitable for the HOM electronics. Two data analysis techniques are used and compared in extracting beam position information from the dipole HOMs: direct linear regression and singular value decomposition. Current experiments suggest a resolution of 50 m accuracy in predicting local beam position using modes in the fifth dipole band, and a global resolution of 20 m over the complete module. Based on these results we decided to build a HOM electronics for the second dipole band and the fifth dipole band, so that we will have both high resolution measurements for the whole module, and localized measurements for individual cavity. The prototype electronics is being built by Fermilab and planned to be tested in FLASH by the end of 2012.

  13. Galvanometer deflection: a precision high-speed system.

    Science.gov (United States)

    Jablonowski, D P; Raamot, J

    1976-06-01

    An X-Y galvanometer deflection system capable of high precision in a random access mode of operation is described. Beam positional information in digitized form is obtained by employing a Ronchi grating with a sophisticated optical detection scheme. This information is used in a control interface to locate the beam to the required precision. The system is characterized by high accuracy at maximum speed and is designed for operation in a variable environment, with particular attention placed on thermal insensitivity.

  14. Nondegenerate two-mode squeezing and quantum-nondemolition measurements using three-level atoms in a cavity

    Science.gov (United States)

    Poizat, J. Ph.; Collett, M. J.; Walls, D. F.

    1992-04-01

    We consider two modes of the electromagnetic field interacting via a three-level atom in a ladder configuration. We calculate the squeezing spectra of the sum and difference of the two output beams. The usefulness of this system as a quantum-nondemolition-measurement scheme is analyzed and a prediction is made using the parameters of a recent experiment by Grangier et al. [Phys. Rev. Lett. 66, 1418 (1991)]. We use a full three-level model in the most general case and in particular the influence of both the one-photon and the two-photon detunings are investigated.

  15. Stable single-polarization single-longitudinal-mode linear cavity erbium-doped fiber laser based on structured chirped fiber Bragg grating.

    Science.gov (United States)

    Yin, Bin; Liu, Zhibo; Feng, Suchun; Bai, Yunlong; Li, Haisu; Jian, Shuisheng

    2015-01-01

    A novel linear cavity erbium-doped fiber (EDF) laser based on a structured chirped fiber Bragg grating (CFBG) filter is proposed for stable single-polarization (SP) single-longitudinal-mode (SLM) operation. For the first time, to the best of our knowledge, a structured CFBG filter with an ultranarrow transmission band which is generated by tapering directly on CFBG is used to select the laser longitudinal mode. The SLM operation is obtained by using the structured CFBG together with an unpumped EDF acting as a saturable absorber. The fluctuations of the laser peak power and center wavelength are less than 0.07 dB and 1 pm in 1 h, respectively. The stable SP operation is achieved by using the inline broadband polarizer. The measured 20 dB laser linewidth is about 27.7 kHz, which indicates the laser linewidth is approximately 1.39 kHz FWHM.

  16. Laser self-mixing interferometry in VCSELs - an ultra-compact and massproduceable deflection detection system for nanomechanical polymer cantilever sensors

    DEFF Research Database (Denmark)

    Larsson, David; Yvind, Kresten; Hvam, Jørn Märcher;

    2008-01-01

    We have realised an ultra-compact deflection detection system based on laser self-mixing interferometry in a Vertical-Cavity Surface-Emitting Laser (VCSEL). The system can be used together with polymer nanomechanical cantilevers to form chemical sensors capable of detecting less than 1nm deflection....

  17. NUMERICAL SIMULATION OF CAVITY FLOW AND FLOW OVER AIRCRAFT COMPARTMENT USING SEMI-EMPIRICAL TURBULENCE MODELS

    Directory of Open Access Journals (Sweden)

    2016-01-01

    Full Text Available The article is devoted to the validation and application of CFD code for turbulent flows. Two-dimensional un- steady flows in the cavities and compartments and three-dimensional flow in the compartment of complex geometry have been considered. Two turbulence parameter oriented models are used.Numerical simulation of unsteady transonic flow (Mоо=0.74 in a narrow channel with a cavity inside has been conducted. The dependence of the static pressure on time at fixed points in space has been obtained. The fast Fourier trans- form has been applied for processing data of static pressure. The difference of 6-10% between the numerical and experi-mental data has been obtained.The computations of unsteady transonic cavity flow with Mach number Mоо=0.85 have been performed. Low fre- quency oscillations of the static pressure in several fixed points in space have been obtained. Power spectrum of oscilla- tions at the center of the cavity is compared with experimental data and Rossiter modes. An acceptable agreement between experimental and computed data has been achieved. The influence of geometrical factors on the frequency characteristics of the flow has been investigated. For this purpose two round flaps have been added to the cavity. The most low-frequency oscillation modes changed by the presence of the flaps. The first mode was gone, the second mode amplitude decreased and the third mode amplitude significantly decreased. The changes in height of protruding part of the geometry to the external flow have led to changes in pressure pulsation amplitude without changing the frequency. The spectral functions obtained while using the two considered models of turbulence have been compared for this case. It is found that the frequency values are only slightly different; the main difference is present at the amplitude of pulsations.The effect of deflection of flat flap on the non-stationary subsonic flow parameters in a cylindrical body with an inner

  18. Field distribution analysis in deflecting structures

    Energy Technology Data Exchange (ETDEWEB)

    Paramonov, V.V. [Joint Inst. for Nuclear Research, Moscow (Russian Federation)

    2013-02-15

    Deflecting structures are used now manly for bunch rotation in emittance exchange concepts, bunch diagnostics and to increase the luminosity. The bunch rotation is a transformation of a particles distribution in the six dimensional phase space. Together with the expected transformations, deflecting structures introduce distortions due to particularities - aberrations - in the deflecting field distribution. The distributions of deflecting fields are considered with respect to non linear additions, which provide emittance deteriorations during a transformation. The deflecting field is treated as combination of hybrid waves HE{sub 1} and HM{sub 1}. The criteria for selection and formation of deflecting structures with minimized level of aberrations are formulated and applied to known structures. Results of the study are confirmed by comparison with results of numerical simulations.

  19. Mechanical radiation detection via sub-Brownian lever deflections

    Science.gov (United States)

    Hammig, Mark David

    2005-07-01

    A micromechanical lever that deflects in response to the impacts of charged particles is proposed as a means of improving upon the capabilities of existing radiation detection technology. When a particle strikes an object, momentum is transferred to the impacted body. The resulting body motion can be correlated to the energy of the incident particle. The momentum detector offers promise as a highly discriminating, high-resolution tool for ion sensing. Advances required to successfully realize a spectroscopic capability have been completed; specifically, techniques for reproducibly fabricating micromechanical structures have been optimized, and an instrument that measures miniscule deflections has been developed. Even absent substantial refinement efforts, the novel coupled-cavity optical detector can resolve lever motions on the order of 1--10 picometers. A method by which the Brownian motion of the lever can be stilled has been proven which elicits reductions sufficient to measure heavy-ion impact, the deflections from which may be several orders of magnitude below the thermal vibration amplitude. Using active forcing techniques, the Brownian vibration of the microlevers has been reduced from room temperature (288 K) to sub-Kelvin temperatures, for levers vibrating in air. The mechanical factors that limit the noise reduction magnitude are discussed and methods of surmounting those limitations are identified.

  20. Sagnac interferometer for photothermal deflection spectroscopy.

    Science.gov (United States)

    Shiokawa, Naoyuki; Mizuno, Yuki; Tsuchiya, Harumasa; Tokunaga, Eiji

    2012-07-01

    Photothermal deflection spectroscopy is combined with a Sagnac interferometer to enhance the sensitivity of the absorption measurement by converting the photothermal beam deflection effect into the light intensity change by the interference effect. Because of stable light interference due to the common path, the signal intensity can be amplified without increasing the noise by extending the optical path length between a sample and a photodetector. The sensitivity is further improved by the use of focusing optics and double-pass geometry. This makes photothermal deflection spectroscopy applicable to any kind of material in the whole visible region with a xenon lamp for excitation and water or air as a deflection medium.

  1. Effects of Disorder on Mode of Photonic Crystal Bragg Cavity%介质层厚度无序对Bragg微腔模式的影响

    Institute of Scientific and Technical Information of China (English)

    郑改革; 史林兴; 王海娇; 蒋立勇; 李相银

    2009-01-01

    采用本征模展开法(EME)结合完全匹配层(PML)边界条件,研究了由TiO2和SiO2复合膜结构组成的平面光子晶体Bragg微腔的模式特性,分析了介质厚度无序对微腔模式的调制以及入射角对局域长度的影响.结果表明,若光束正入射,带边局域长度要大于禁带局域长度,随着无序度的增加光子通带的透过率逐渐降低,而禁带的透过率逐渐上升.当无序度较小时,局域长度随随机度的变化在带边和禁带内表现出相反的规律.当无序度较大时,局域长度不仅和随机度、带隙有关,还受到材料的影响;若光束斜入射,TE模的局域长度要远小于TM模对应的值,且其最小值向短波方向移动.此外,入射角和膜层数的变化都会导致局域长度的起伏.%Based on eigen-mode expansion method (EME) and perfectly matched layer (PML) absorbing boundary condition, the properties of the mode of planar photonic crystal Bragg cavity, which was composed of TiO2and SiO2 bi-layers,were investigated. The study of localization behavior in a randomly layered medium was extended from normal to oblique incidence,and both TE and TM modes were considered. The effects of disorder and incident angle on the mode and the localization length of the cavity are studied in detail. The localization length was found to be very small in gaps and much larger in edge regions.The transmission decreases in edges while increases in gaps as the disordering degree increases .The results show that when light incidents upon the system and if the disordering degree is small, the localization length of the edge is lager than the one in the gap, and their relationship with disordering degree is different. When the disordering degree increases, localization length is affected not only by disordering degree and photonic band gap, but also the material. Moreover, the localization length can be changed with period and incident angle, and its behaviors are very different for TE

  2. A geometrically non-linear formulation of a three-dimensional beam element for solving large deflection multibody system problems

    NARCIS (Netherlands)

    Jonker, J.B.; Meijaard, J.P.

    2013-01-01

    A beam finite element formulation for large deflection problems in the analysis of flexible multibody systems has been proposed. In this formulation, a set of independent discrete deformation modes are defined for each element which are related to conventional small deflection beam theory in a co-ro

  3. Deflection Control in Rigid Pavements

    Science.gov (United States)

    Varunkrishna, Nulu; Jayasankar, R.

    2017-07-01

    The need for modern transportation systems together with the high demand for perpetual pavements under the drastically increasing applied loads has led to a great deal of research on concrete as a pavement material worldwide. This research indeed instigated many modifications in concrete aiming for improving the concrete properties. Pavement Quality Concrete requires higher flexural strength and fewer deflections in hardened state. Fiber reinforcement and latex modification are two reliable approaches serving the required purposes. The concrete made with these two modifications is called Polymer-modified Fiber-reinforced concrete. The present study deals with the usage of polypropylene as fiber and SBR (Styrene Butadiene Rubber) Latex as polymer. M30 grade concrete was modified by replacing cement with two different percentages of fiber (0.5%, 1.0% of weight of cement) and with three different percentages of SBR latex (10%, 15% & 20% of weight of cement).

  4. Reduction of RF accelerating voltage of Pohang Light Source-II superconducting RF cavity for stable top-up mode operation

    Science.gov (United States)

    Joo, Y.; Yu, I.; Park, I.; Chun, M. H.; Sohn, Y.

    2017-03-01

    The Pohang Light Source-II (PLS-II) is currently providing a top-up mode user-service operation with maximum available beam current of 400 mA and a beam emittance of below 10 nm-rad. The dimension of the beam bunch shortened to accomplish a low beam emittance of below 10 nm-rad from a high beam current of 400 mA increases the bunch charge density. As a result, the electron beam lifetime is significantly degraded and a high gradient of power is lost in the vacuum components of the storage ring. A study on how to reduce the bunch charge density without degrading beam emittance found that reducing the RF accelerating voltage (Vacc) can lower the bunch charge density by lengthening the bunch in the longitudinal direction. In addition, the Vacc required for stable operation with beam current of 400 mA can be reduced by lowering the external cavity quality factors (Qext values) of the superconducting cavities (SCs). To control the Qext values of SCs gradually without accessing the accelerator tunnel, a remote control motorized three-probe-tuner was installed in the transmission line of each SC. The optimum installation position of the three-probe-tuner was determined by using a finite-difference time-domain (FDTD) simulation and by experimenting on various installation positions of the three-probe-tuner. The Qext values of all the SCs were lowered to 1.40 × 105, and then, the Vacc required to store the beam current of 400 mA was decreased from 4.8 MV to 4.2 MV, which corresponds to 10% lengthening of the beam bunches. The stable operation with the reduced Vacc was confirmed during a 400 mA ten-day top-up mode user-service. Currently, the RF system of the PLS-II storage ring delivers the user-service operation with lowered Qext values to reduce the power loss at the vacuum components as well as the cryogenic heat load of SCs, and no significant problems have been found. This method of reducing the Vacc may also be applied in other synchrotron facilities.

  5. Cavity magnomechanics

    Science.gov (United States)

    Zou, Chang-Ling; Zhang, Xufeng; Jiang, Liang; Tang, Hong

    2016-05-01

    Recently, cavity magnonics has attracted much attention for potential applications of coherent information transduction and hybrid quantum devices. The magnon is a collective spin wave excitation in ferromagnetic material. It is magnetically tunability, with long coherence time and non-reciprocical interaction with electro-magnetic fields. We report the coherent coupling between magnon, microwave photon and phonon. First, we demonstrate strong coupling and ultrastrong coupling between the magnon in YIG sphere and microwave photon in three-dimensional cavity. Then, based on the hybridized magnon-photon modes, we observe the triply resonant magnon-mcirowave photon-phonon coupling, where the ultrahigh-Q mechanical vibration of YIG sphere is dispersively coupled with the magnon via magnetostrictive interaction. We observe interesting phenomena, including electromagnetically induced transparency/absorption and parametric amplification. In particular, benefit from the large tunability of the magnon, we demonstrate a tunable microwave amplifier with gain as high as 30 dB. The single crystal YIG also has excellent optical properties, and thus provide a unique platform bridging MHz, GHz and THz information carriers. Finally, we present the latest progress towards coherent magnon to optical photon conversion.

  6. Novel Geometries for the LHC Crab Cavity

    Energy Technology Data Exchange (ETDEWEB)

    B. Hall, G. Burt, C. Lingwood, R. Rimmer, H. Wang

    2010-05-23

    The planned luminosity upgrade to LHC is likely to necessitate a large crossing angle and a local crab crossing scheme. For this scheme crab cavities align bunches prior to collision. The scheme requires at least four such cavities, a pair on each beam line either side of the interaction point (IP). Upstream cavities initiate rotation and downstream cavities cancel rotation. Cancellation is usually done at a location where the optics has re-aligned the bunch. The beam line separation near the IP necessitates a more compact design than is possible with elliptical cavities such as those used at KEK. The reduction in size must be achieved without an increase in the operational frequency to maintain compatibility with the long bunch length of the LHC. This paper proposes a suitable superconducting variant of a four rod coaxial deflecting cavity (to be phased as a crab cavity), and presents analytical models and simulations of suitable designs.

  7. Performance analysis of a two-state quantum heat engine working with a single-mode radiation field in a cavity

    Science.gov (United States)

    Wang, Jianhui; He, Jizhou; He, Xian

    2011-10-01

    We present a performance analysis of a two-state heat engine model working with a single-mode radiation field in a cavity. The heat engine cycle consists of two adiabatic and two isoenergetic processes. Assuming the wall of the potential moves at a very slow speed, we determine the optimization region and the positive work condition of the heat engine model. Furthermore, we generalize the results to the performance optimization for a two-state heat engine with a one-dimensional power-law potential. Based on the generalized model with an arbitrary one-dimensional potential, we obtain the expression of efficiency as η=1-(EC)/(EH), with EH (EC) denoting the expectation value of the system Hamiltonian along the isoenergetic process at high (low) energy. This expression is an analog of the classical thermodynamical result of Carnot, ηc=1-(TC)/(TH), with TH (TC) being the temperature along the isothermal process at high (low) temperature. We prove that under the same conditions, the efficiency η=1-(EC)/(EH) is bounded from above the Carnot efficiency, ηc=1-(TC)/(TH), and even quantum dynamics is reversible.

  8. Tailoring surface plasmon resonance and dipole cavity plasmon modes of scattering cross section spectra on the single solid-gold/gold-shell nanorod

    Energy Technology Data Exchange (ETDEWEB)

    Chou Chau, Yuan-Fong, E-mail: chou.fong@ubd.edu.bn; Lim, Chee Ming; Kumara, N. T. R. N.; Yoong, Voo Nyuk [Centre for Advanced Material and Energy Sciences, Universiti Brunei Darussalam, Tungku Link, Gadong BE1410, Brunei (Brunei Darussalam); Lee, Chuanyo [Department of Electronic Engineering, Chien Hsin University of Science and Technology, No. 229, Jianxing Rd., Zhongli City, Taoyuan County 32097, Taiwan (China); Huang, Hung Ji; Lin, Chun-Ting [Instrument Technology Research Center, National Applied Research Laboratories, Hsinchu, Taiwan (China); Chiang, Hai-Pang [Institute of Optoelectronic Sciences, National Taiwan Ocean University, Keelung 202, Taiwan (China)

    2016-09-07

    Tunable surface plasmon resonance (SPR) and dipole cavity plasmon modes of the scattering cross section (SCS) spectra on the single solid-gold/gold-shell nanorod have been numerically investigated by using the finite element method. Various effects, such as the influence of SCS spectra under x- and y-polarizations on the surface of the single solid-gold/gold-shell nanorod, are discussed in detail. With the single gold-shell nanorod, one can independently tune the relative SCS spectrum width by controlling the rod length and rod diameter, and the surface scattering by varying the shell thickness and polarization direction, as well as the dipole peak energy. These behaviors are consistent with the properties of localized SPRs and offer a way to optically control and produce selected emission wavelengths from the single solid-gold/gold-shell nanorod. The electric field and magnetic distributions provide us a qualitative idea of the geometrical properties of the single solid-gold/gold-shell nanorod on plasmon resonance.

  9. Dielectric properties of oil sands at 2.45 GHz with TE1,0,11 mode determined by a rectangular cavity resonator.

    Science.gov (United States)

    Erdogan, Levent; Akyel, Cevdet; Ghannouchi, Fadhel M

    2011-01-01

    Oil obtained from oil sands resources constitute an important portion of the oil industry in Canada. Extraction of the bitumen from oil sands is very crucial process because of its cost and environmental impact. Microwave energy applicators by heating oil sands at microwave frequencies can be an excellent alternative to extract bitumen with the advantages of being potentially cost-effective and environmentally friendly method of extraction. In order to design and manufacture a microwave energy applicator, its dielectric properties must be known. In this study, as the first part of our ultimate microwave energy applicator project, in advance, the complex permittivity of oil sands was measured by using rectangular cavity resonator, designed and fabricated in Ecole Polytechnique de Montréal laboratories, at 2.45 GHz with TE1,0,1 mode. The accuracy of the permittivity measurement results obtained with the developed system was verified against those obtained using a commercial open-ended probe system as well the values of well known materials documented in open literature. Since there is no study found in the literature about the complex permittivity values of oil sands at 2.45 GHz, the present study would be of great help and important guide for those who plan to design and manufacture microwave energy applicators in order to extract the bitumen from the oil sands.

  10. Evaluation of cuspal deflection in premolar teeth restored with low shrinkable resin composite (in vitro study).

    Science.gov (United States)

    Labib, Labib Mohamed; Nabih, Sameh Mahmoud; Baroudi, Kusai

    2015-01-01

    This study evaluated cuspal deflection in premolar teeth restored with low shrinkable resin composite. A total of 40 human premolars were used for cuspal deflection evaluation in this study. Each group was divided into four equal groups according to the type of resin composite and the adhesive used as follows: group A: Using low shrinkable resin composite (silorane) with its adhesive system; group B: Using low shrinkable composite (silorane) with G-bond; group C: Using Filtek Z350 composite with G-bond; and group D: Using Filtek Z350 composite with AdheSE. Cusp deflection was detected using Universal measuring microscope and laser horizontal metroscope. This study was done to investigate the effect of polymerization shrinkage stresses of two resin composite materials (Filtek Z350 and Filtek P90) on cuspal deflection of mesio-occluso-distal restoration. For this study, the extracted non-carious maxillary second premolars were selected. Forty teeth that showed no more than 5% variation in their dimensions were used. A significant increase in cuspal deflection of cavities restored with the methacrylate-based (Filtek Z350) compared with the silorane (P90) resin-based composites was obtained. The change in the organic matrix or materials formulation of the resin composite using silorane has a positive effect on controlling the cusp deflection.

  11. X-Band Crab Cavities for the CLIC Beam Delivery System

    Energy Technology Data Exchange (ETDEWEB)

    Burt, G.; Ambattu, P.K.; Dexter, A.C.; Abram, T.; /Cockcroft Inst. Accel. Sci. Tech. /Lancaster U.; Dolgashev, V.; Tantawi, S.; /SLAC; Jones, R.M.; /Cockcroft Inst. Accel. Sci. Tech. /Manchester U.

    2011-11-22

    The CLIC machine incorporates a 20 mrad crossing angle at the IP to aid the extraction of spent beams. In order to recover the luminosity lost through the crossing angle a crab cavity is proposed to rotate the bunches prior to collision. The crab cavity is chosen to have the same frequency as the main linac (11.9942 GHz) as a compromise between size, phase stability requirements and beam loading. It is proposed to use a HE11 mode travelling wave structure as the CLIC crab cavity in order to minimise beam loading and mode separation. The position of the crab cavity close to the final focus enhances the effect of transverse wake-fields so effective wake-field damping is required. A damped detuned structure is proposed to suppress and de-cohere the wake-field hence reducing their effect. Design considerations for the CLIC crab cavity will be discussed as well as the proposed high power testing of these structures at SLAC. Design of a crab cavity for CLIC is underway at the Cockcroft Institute in collaboration with SLAC. This effort draws on a large degree of synergy with the ILC crab cavity developed at the Cockcroft Institute and other deflecting structure development at SLAC. A study of phase and amplitude variations in the cavity suggests that the tolerances are very tight and require a 'beyond state of the art' LLRF control system. A study of cavity geometry and its effect on the cavity fields has been performed using Microwave studio. This study has suggested that for our cavity an iris radius between 4-5 mm is optimum with an iris thickness of 2-3 mm based on group velocity and peak fields. A study of the cavity wakefields show that the single bunch wakes are unlikely to be a problem but the short bunch spacing may cause the multi-bunch wakefields to be an issue. This will require some of the modes to be damped strongly so that the wake is damped significantly before any following bunch arrives. Various methods of damping have been investigated and

  12. X-Band Crab Cavities for the CLIC Beam Delivery System

    Energy Technology Data Exchange (ETDEWEB)

    Burt, G.; Ambattu, P.K.; Dexter, A.C.; Abram, T.; /Cockcroft Inst. Accel. Sci. Tech. /Lancaster U.; Dolgashev, V.; Tantawi, S.; /SLAC; Jones, R.M.; /Cockcroft Inst. Accel. Sci. Tech. /Manchester U.

    2011-11-22

    The CLIC machine incorporates a 20 mrad crossing angle at the IP to aid the extraction of spent beams. In order to recover the luminosity lost through the crossing angle a crab cavity is proposed to rotate the bunches prior to collision. The crab cavity is chosen to have the same frequency as the main linac (11.9942 GHz) as a compromise between size, phase stability requirements and beam loading. It is proposed to use a HE11 mode travelling wave structure as the CLIC crab cavity in order to minimise beam loading and mode separation. The position of the crab cavity close to the final focus enhances the effect of transverse wake-fields so effective wake-field damping is required. A damped detuned structure is proposed to suppress and de-cohere the wake-field hence reducing their effect. Design considerations for the CLIC crab cavity will be discussed as well as the proposed high power testing of these structures at SLAC. Design of a crab cavity for CLIC is underway at the Cockcroft Institute in collaboration with SLAC. This effort draws on a large degree of synergy with the ILC crab cavity developed at the Cockcroft Institute and other deflecting structure development at SLAC. A study of phase and amplitude variations in the cavity suggests that the tolerances are very tight and require a 'beyond state of the art' LLRF control system. A study of cavity geometry and its effect on the cavity fields has been performed using Microwave studio. This study has suggested that for our cavity an iris radius between 4-5 mm is optimum with an iris thickness of 2-3 mm based on group velocity and peak fields. A study of the cavity wakefields show that the single bunch wakes are unlikely to be a problem but the short bunch spacing may cause the multi-bunch wakefields to be an issue. This will require some of the modes to be damped strongly so that the wake is damped significantly before any following bunch arrives. Various methods of damping have been investigated and

  13. Directed energy deflection laboratory measurements

    Science.gov (United States)

    Brashears, Travis; Lubin, Phillip; Hughes, Gary B.; Meinhold, Peter; Suen, Jonathan; Batliner, Payton; Motta, Caio; Griswold, Janelle; Kangas, Miikka; Johansson, Isbella; Alnawakhtha, Yusuf; Prater, Kenyon; Lang, Alex; Madajian, Jonathan

    2015-09-01

    We report on laboratory studies of the effectiveness of directed energy planetary defense as a part of the DESTAR (Directed Energy System for Targeting of Asteroids and exploRation) program. DE-STAR [1][5][6] and DE-STARLITE [2][5][6] are directed energy "stand-off" and "stand-on" programs, respectively. These systems consist of a modular array of kilowatt-class lasers powered by photovoltaics, and are capable of heating a spot on the surface of an asteroid to the point of vaporization. Mass ejection, as a plume of evaporated material, creates a reactionary thrust capable of diverting the asteroid's orbit. In a series of papers, we have developed a theoretical basis and described numerical simulations for determining the thrust produced by material evaporating from the surface of an asteroid [1][2][3][4][5][6]. In the DE-STAR concept, the asteroid itself is used as the deflection "propellant". This study presents results of experiments designed to measure the thrust created by evaporation from a laser directed energy spot. We constructed a vacuum chamber to simulate space conditions, and installed a torsion balance that holds an "asteroid" sample. The sample is illuminated with a fiber array laser with flux levels up to 60 MW/m2 which allows us to simulate a mission level flux but on a small scale. We use a separate laser as well as a position sensitive centroid detector to readout the angular motion of the torsion balance and can thus determine the thrust. We compare the measured thrust to the models. Our theoretical models indicate a coupling coefficient well in excess of 100 μN/Woptical, though we assume a more conservative value of 80 μN/Woptical and then degrade this with an optical "encircled energy" efficiency of 0.75 to 60 μN/Woptical in our deflection modeling. Our measurements discussed here yield about 45 μN/Wabsorbed as a reasonable lower limit to the thrust per optical watt absorbed.

  14. Composite resonator vertical cavity laser diode

    Energy Technology Data Exchange (ETDEWEB)

    Choquette, K.D.; Hou, H.Q.; Chow, W.W.; Geib, K.M.; Hammons, B.E.

    1998-05-01

    The use of two coupled laser cavities has been employed in edge emitting semiconductor lasers for mode suppression and frequency stabilization. The incorporation of coupled resonators within a vertical cavity laser opens up new possibilities due to the unique ability to tailor the interaction between the cavities. Composite resonators can be utilized to control spectral and temporal properties within the laser; previous studies of coupled cavity vertical cavity lasers have employed photopumped structures. The authors report the first composite resonator vertical cavity laser diode consisting of two optical cavities and three monolithic distributed Bragg reflectors. Cavity coupling effects and two techniques for external modulation of the laser are described.

  15. Cavity-Beam-Transmitter Interaction Formula Collection with Derivation

    CERN Document Server

    Tückmantel, J

    2010-01-01

    The fundamental beam-cavity-transmitter relations for accelerating and deflecting/crab cavities are presented for steady state and time-varying situations. For completeness a compact proof of the Panofsky-Wenzel theorem is given and the fundamental beam loading theorem is derived.Also the determination of relative bunch form factors is shown.

  16. Cavity QED by the Numbers

    Science.gov (United States)

    Kimble, H. J.; Boca, A.; Boozer, A. D.; Bowen, W. P.; Buck, J. R.; Chou, C. W.; Duan, L.-M.; Kuzmich, A.; McKeever, J.

    2004-12-01

    Observations of cooling and trapping of N = 1,2,3,... atoms inside a small optical cavity are described. The atom-cavity system operates in a regime of strong coupling for which single photons are sufficient to saturate the atomic response. New theoretical protocols for the efficient engineering of multi-atom entanglement within the setting of cavity QED are described. By trapping a single atom within the cavity mode, a one-atom laser is experimentally realized in a regime of strong coupling. Beyond the setting of cavity QED, quantum correlations have been observed for photon pairs emitted from an atomic ensemble and with a programmable time offset.

  17. Large Deflections of Elastic Rectangular Plates

    Science.gov (United States)

    Razdolsky, A. G.

    2015-11-01

    It is known that elastic large deflections of thin plates are governed by von Karman nonlinear equations. The analytical solution of these equations in the general case is unfeasible. Samuel Levy, in 1942, showed that large deflections of the rectangular plate can be expressed as a double series of sine-shaped harmonics (deflection harmonics). However, this method gave no way of creating the computer algorithm of solving the problem. The stress function expression taken in the Levy's method must be revised to find the approach that takes into account of all possible products of deflection coefficients. The algorithm of solving the problem for the rectangular plate with an arbitrary aspect ratio under the action of the lateral distributed load is reported in this paper. The approximation of the plate deflection is taken in the form of double series proposed by Samuel Levy. However, the expression for the stress function is presented in the form that incorporates products of deflection coefficients in the explicit form in distinction to the Levy's expression. The number of harmonics in the deflection expression may be arbitrary. The algorithm provides composing the system of governing cubic equations, which includes the deflection coefficients in the explicit form. Solving the equation system is based on using the principle of minimum potential energy. A method of the gradient descent is applied to find the equilibrium state of the plate as the minimum point of the potential energy. A computer program is developed on the basis of the present algorithm. Numerical examples carried out for the plate model with 16 deflection harmonics illustrate the potentialities of the program. The results of solving the examples are presented in the graphical form for the plates with a different aspect ratio and may be used under designing thin-walled elements of airplane and ship structures.

  18. Ion Beam Shepherd for Asteroid Deflection

    CERN Document Server

    Bombardelli, C

    2011-01-01

    We present a novel concept to impart a continuous thrust to an Earth threatening asteroid from a hovering spacecraft without need for physical attachment nor gravitational interaction with the asteroid. The concept involves an ion thruster placed at a distance of a few asteroid diameters directing a stream of quasi-neutral plasma against the asteroid surface resulting into a net transferred momentum. As the transmitted force is independent of the asteroid mass and size the method allows deflecting subkilometer asteroids with a spacecraft much lighter when compared to a gravity tractor spacecraft of equal deflection capability. The finding could make low-cost asteroid deflection missions possible in the coming years.

  19. Dental cavities

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/article/001055.htm Dental cavities To use the sharing features on this page, please enable JavaScript. Dental cavities are holes (or structural damage) in the ...

  20. Frittage micro-ondes en cavité monomode de biocéramiques Microwaves sintering of bioceramics in a single mode cavity

    Directory of Open Access Journals (Sweden)

    Savary Etienne

    2013-11-01

    Full Text Available Le but premier de cette étude est de montrer la faisabilité du frittage direct en cavité micro-ondes monomode de deux biomatériaux céramiques : l'hydroxyapatite et le phosphate tri-calcique. Ainsi, cette étude montre que ce procédé a permis d'obtenir, en des temps très courts, inférieurs à 20 minutes, des échantillons denses présentant des microstructures fines. Les caractérisations mécaniques sur les échantillons frittés par micro-ondes ont révélé des valeurs de module d'élasticité et de dureté supérieures à celles généralement obtenues sur des échantillons frittés de manière conventionnelle. Ces résultats sont discutés en fonction de la microstructure obtenue et des différents paramètres expérimentaux : granulométrie des poudres, température de frittage, temps d'irradiation micro-ondes. The main purpose of this study consists in investigating the direct microwaves sintering in a single mode cavity of two bioceramics: hydroxyapatite and tri-calcium phosphate. Thus, dense samples presenting fine microstructures are successfully obtained in less than 20 minutes of irradiation. The resulting mechanical characterizations on microwaves sintered samples evidence higher Young's modulus and hardness values than those usually reported on conventionally sintered samples. Those results are discussed according to the microstructures observed and the experimental parameters such as powders granulometries, sintering temperatures, microwaves irradiation times.

  1. Design and studies on the traveling wave transverse RF deflecting structure

    Institute of Scientific and Technical Information of China (English)

    ZHANG Jing-Ru; HOU Mi; DAI Jian-Ping; PEI Shi-Lun; PEI Guo-Xi

    2008-01-01

    With the development of free electron laser (FEL) and the international linear collider (ILC), the electron bunch length is getting smaller and smaller. The traveling-wave transverse RF deflecting structure is an important part of the RF deflecting method for bunch length measurement and phase space diagnostics.The operation mode in RF deflector is the "TM11-like" mode. Since the TM11-like mode in this structure has a pair of degenerate dipole modes, two additional holes are provided on either side of each iris to stabilize the mode. The simulation and optimization have been done. A prototype has been fabricated and tested. The cold test results have been compared with the simulations of the first three modes.

  2. Alaska North-South Deflections (DEFLEC96)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This 2' x 4' surface deflection of the vertical grid for Alaska is the DEFLEC96 model. The computation used about 1.1 million terrestrial and marine gravity data...

  3. Mexico East-West Deflections (DMEX97)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This 2' surface deflection of the vertical grid for Mexico, and North-Central is the DMEX97 model. The computation used about one million terrestrial and marine...

  4. Alaska East-West Deflections (DEFLEC96)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This 2' x 4' surface deflection of the vertical grid for Alaska is the DEFLEC96 model. The computation used about 1.1 millionterrestrial and marine gravity data held...

  5. Mexico North-South Deflections (DMEX97)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This 2' surface deflection of the vertical grid for Mexico, and North-Central is the DMEX97 model. The computation used about one million terrestrial and marine...

  6. Crab Cavities for Linear Colliders

    Energy Technology Data Exchange (ETDEWEB)

    Burt, G.; Ambattu, P.; Carter, R.; Dexter, A.; Tahir, I.; /Cockcroft Inst. Accel. Sci. Tech. /Lancaster U.; Beard, C.; Dykes, M.; Goudket, P.; Kalinin, A.; Ma, L.; McIntosh, P.; /Daresbury; Shulte, D.; /CERN; Jones, Roger M.; /Cockcroft Inst. Accel. Sci. Tech. /Manchester U.; Bellantoni, L.; Chase, B.; Church, M.; Khabouline, T.; Latina, A.; /Fermilab; Adolphsen, C.; Li, Z.; Seryi, Andrei; /SLAC

    2011-11-08

    Crab cavities have been proposed for a wide number of accelerators and interest in crab cavities has recently increased after the successful operation of a pair of crab cavities in KEK-B. In particular crab cavities are required for both the ILC and CLIC linear colliders for bunch alignment. Consideration of bunch structure and size constraints favour a 3.9 GHz superconducting, multi-cell cavity as the solution for ILC, whilst bunch structure and beam-loading considerations suggest an X-band copper travelling wave structure for CLIC. These two cavity solutions are very different in design but share complex design issues. Phase stabilisation, beam loading, wakefields and mode damping are fundamental issues for these crab cavities. Requirements and potential design solutions will be discussed for both colliders.

  7. Crab cavities for linear colliders

    CERN Document Server

    Burt, G; Carter, R; Dexter, A; Tahir, I; Beard, C; Dykes, M; Goudket, P; Kalinin, A; Ma, L; McIntosh, P; Shulte, D; Jones, Roger M; Bellantoni, L; Chase, B; Church, M; Khabouline, T; Latina, A; Adolphsen, C; Li, Z; Seryi, Andrei; Xiao, L

    2008-01-01

    Crab cavities have been proposed for a wide number of accelerators and interest in crab cavities has recently increased after the successful operation of a pair of crab cavities in KEK-B. In particular crab cavities are required for both the ILC and CLIC linear colliders for bunch alignment. Consideration of bunch structure and size constraints favour a 3.9 GHz superconducting, multi-cell cavity as the solution for ILC, whilst bunch structure and beam-loading considerations suggest an X-band copper travelling wave structure for CLIC. These two cavity solutions are very different in design but share complex design issues. Phase stabilisation, beam loading, wakefields and mode damping are fundamental issues for these crab cavities. Requirements and potential design solutions will be discussed for both colliders.

  8. Transverse C-band deflecting structure for longitudinal electron-bunch-diagnosis in XFEL “SACLA”

    Energy Technology Data Exchange (ETDEWEB)

    Ego, H., E-mail: ego@spring8.or.jp [Japan Synchrotron Radiation Research Institute (JASRI), Kouto, Sayo, Hyogo (Japan); Maesaka, H.; Sakurai, T.; Otake, Y. [RIKEN SPring-8 Center, Kouto, Sayo, Hyogo (Japan); Hashirano, T.; Miura, S. [Mitsubishi Heavy Industries, Ltd. (MHI), Itozaki, Mihara, Hiroshima (Japan)

    2015-09-21

    In the 8 GeV compact X-ray FEL “SACLA,” a single bunch of electrons is compressed to a duration of approximately 30 fs to yield a peak current of 3 kA, which creates brilliant self-amplified spontaneous emission. To measure the longitudinal profile of an ultrashort electron bunch and verify the compression, we developed a high-gradient C-band RF deflecting structure 1.8 m long and periodically loaded with racetrack-shaped irises. The irises generated a high deflection gradient for the vertically deflecting HEM11-5π/6 dipole mode and suppressed rotation of the deflection plane. The two structures were fabricated and generated a stable total deflecting voltage exceeding 60 MV and revealed the longitudinal electron-bunch profile with an effective time resolution of approximately 10 fs.

  9. Small angle electron diffraction and deflection

    Directory of Open Access Journals (Sweden)

    T. Koyama

    2012-03-01

    Full Text Available Electron optical system is constructed in order to obtain small angle diffraction and Lorentz deflection of electrons at the order of down to 10-6 radian in the reciprocal space. Long-distance camera length up to 3000 m is achieved in a conventional transmission electron microscope with LaB6 thermal emission type. The diffraction pattern at 5 × 10-6 radian is presented in a carbon replica grating with 500 nm lattice spacing while the magnetic deflection pattern at 2 × 10-5 radian is exhibited in Permalloy elements. A simultaneous recording of electron diffraction and Lorentz deflection is also demonstrated in 180 degree striped magnetic domains of La0.825Sr0.175MnO3.

  10. High peak-power picosecond pulse generation at 1.26 µm using a quantum-dot-based external-cavity mode-locked laser and tapered optical amplifier.

    Science.gov (United States)

    Ding, Y; Aviles-Espinosa, R; Cataluna, M A; Nikitichev, D; Ruiz, M; Tran, M; Robert, Y; Kapsalis, A; Simos, H; Mesaritakis, C; Xu, T; Bardella, P; Rossetti, M; Krestnikov, I; Livshits, D; Montrosset, Ivo; Syvridis, D; Krakowski, M; Loza-Alvarez, P; Rafailov, E

    2012-06-18

    In this paper, we present the generation of high peak-power picosecond optical pulses in the 1.26 μm spectral band from a repetition-rate-tunable quantum-dot external-cavity passively mode-locked laser (QD-ECMLL), amplified by a tapered quantum-dot semiconductor optical amplifier (QD-SOA). The laser emission wavelength was controlled through a chirped volume Bragg grating which was used as an external cavity output coupler. An average power of 208.2 mW, pulse energy of 321 pJ, and peak power of 30.3 W were achieved. Preliminary nonlinear imaging investigations indicate that this system is promising as a high peak-power pulsed light source for nonlinear bio-imaging applications across the 1.0 μm - 1.3 μm spectral range.

  11. Power coupler for the ILC crab cavity

    Energy Technology Data Exchange (ETDEWEB)

    Burt, G.; Dexter, A.; Jenkins, R.; /Lancaster U.; Beard, C.; Goudket, P.; McIntosh, P.A.; /Daresbury; Bellantoni, Leo; /Fermilab

    2007-06-01

    The ILC crab cavity will require the design of an appropriate power coupler. The beam-loading in dipole mode cavities is considerably more variable than accelerating cavities, hence simulations have been performed to establish the required external Q. Simulations of a suitable coupler were then performed and were verified using a normal conducting prototype with variable coupler tips.

  12. Plasmonic Coupled Cavities on Moire Surfaces

    Science.gov (United States)

    Balci, Sinan; Kocabas, Askin; Karabiyik, Mustafa; Kocabas, Coskun; Aydinli, Atilla

    2010-03-01

    We investigate surface plasmon polariton (SPP) coupled cavity modes on Moire surfaces. An experimental study has been made of the propagation of SPPs on a thin silver surface that is textured with Moire surface pattern using interference lithography. The Moire surface contains periodic array of one dimensional cavities. The distance between the cavities can be controlled by changing the periodicities of Moire surface. When the SPP cavity separation is sufficiently small, we show splitting of strongly coupled plasmonic cavity modes through numerical simulations. Conversely, when the SPP cavity separation is sufficiently large, SPP cavity modes are found to be localized and do not show splitting of SPP cavity modes . This splitting of SPP cavity modes are well explained with a tight binding model that has been succesfully applied in photonic coupled cavities. Reflection measurements and numerical simulation of a large number of adjacent SPP cavities have shown a coupled resonator optical waveguide (CROW) type plasmonic waveguide band formation within the band gap region of unperturbed uniform grating.

  13. The adhesive potential of dentin bonding systems assessed using cuspal deflection measurements and cervical microleakage scores.

    Science.gov (United States)

    Sultan, Ahmed; Moorthy, Advan; Fleming, Garry J P

    2014-10-01

    To assess the cuspal deflection and cervical microleakage of standardized mesio-occluso-distal (MOD) cavities restored with a dimethacrylate resin-based-composite (RBC) placed with one 3-step, one 2-step and three 1-step bonding systems and compared with the unbound condition. Forty-eight sound maxillary premolar teeth with standardized MOD cavities were randomly allocated to six groups. Restoration was performed in eight oblique increments using a quartz-tungsten-halogen (QTH) light curing unit (LCU) with the bonding condition as the dependent variable. Buccal and palatal cuspal deflections were recorded post-irradiation using a twin channel deflection measuring gauge at 0, 30, 60 and 180s. Following restoration, the teeth were thermocycled, immersed in a 0.2% basic fuchsin dye for 24h, sectioned and examined for cervical microleakage assessment. The mean total cuspal deflection measurements with the one 3-step, one 2-step and three 1-step bonding systems were 11.26 (2.56), 10.95 (2.16), 10.03 (2.05) (Futurabond(®) DC SingleDose), 6.37 (1.37) (Adper™ Prompt™ L-Pop™), 8.98 (1.34) μm (All-Bond SE(®)), respectively when compared with the unbound condition (6.46 (1.88) μm) The one-way ANOVA of the total cuspal deflection measurements identified statistical differences (pbonding system although differences between the bonding systems were evident (pbonding technologies available to practitioners for RBCs. Poorly performing adhesives can be identified which indicated the technique may be useful as a screening tool for assessing existing and new bonding technologies which offers the potential to limit complications routinely encountered with Class II RBC restorations. Copyright © 2014 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  14. Hybrid III-V/SOI single-mode vertical-cavity laser with in-plane emission into a silicon waveguide

    DEFF Research Database (Denmark)

    Park, Gyeong Cheol; Xue, Weiqi; Semenova, Elizaveta;

    2015-01-01

    We report a III-V-on-SOI vertical-cavity laser emitting into an in-plane Si waveguide fabricated by using CMOS-compatible processes. The fabricated laser operates at 1.54 µm with a SMSR of 33 dB and a low threshold.......We report a III-V-on-SOI vertical-cavity laser emitting into an in-plane Si waveguide fabricated by using CMOS-compatible processes. The fabricated laser operates at 1.54 µm with a SMSR of 33 dB and a low threshold....

  15. Diffraction-limited Fabry-Perot Cavity in the Near Concentric Regime

    CERN Document Server

    Durak, Kadir; Leong, Victor; Straupe, Stanislav; Kurtsiefer, Christian

    2014-01-01

    Nearly concentric optical cavities can be used to prepare optical fields with a very small mode volume. We implement an anaclastic design of a such a cavity that significantly simplifies mode matching to the fundamental cavity mode. The cavity is shown to have diffraction-limited performance for a mode volume of $\\approx10^4\\lambda^3$. This is in sharp contrast with the behavior of cavities with plano-concave mirrors, where aberrations significantly increase the losses in the fundamental mode. We estimate the related cavity QED parameters and show that the proposed cavity design allows for strong coupling without a need for high finesse or small physical cavity volume.

  16. Mode-locking of an InAs Quantum Dot Based Vertical External Cavity Surface Emitting Laser Using Atomic Layer Graphene

    Science.gov (United States)

    2015-07-16

    disperse the graphene by physical adsorption on its surface. The dispersions are mixed with poly vinyl alcohol (PVA) in a polymer mixer. The...is a more bring color . The bottom structure shows the image of the structure after the incorporation of the GSAM in the VECSEL cavity. The single

  17. Laboratory experiments on arc deflection and instability

    Energy Technology Data Exchange (ETDEWEB)

    Zweben, S.; Karasik, M.

    2000-03-21

    This article describes experiments on arc deflection instability carried out during the past few years at the Princeton University Plasma Physics Laboratory (PPPL). The approach has been that of plasma physicists interested in arcs, but they believe these results may be useful to engineers who are responsible for controlling arc behavior in large electric steel furnaces.

  18. Impeller deflection and modal finite element analysis.

    Energy Technology Data Exchange (ETDEWEB)

    Spencer, Nathan A.

    2013-10-01

    Deflections of an impeller due to centripetal forces are calculated using finite element analysis. The lateral, or out of plane, deflections are an important design consideration for this particular impeller because it incorporates an air bearing with critical gap tolerances. The target gap distance is approximately 10 microns at a rotational velocity of 2500 rpm. The centripetal forces acting on the impeller cause it deflect in a concave fashion, decreasing the initial gap distance as a function of radial position. This deflection is characterized for a previous and updated impeller design for comparative purposes. The impact of design options such as material selection, geometry dimensions, and operating rotational velocity are also explored, followed by a sensitivity study with these parameters bounded by specific design values. A modal analysis is also performed to calculate the impeller's natural frequencies which are desired to be avoided during operation. The finite element modeling techniques continue to be exercised by the impeller design team to address specific questions and evaluate conceptual designs, some of which are included in the Appendix.

  19. Preparation of W state in resonant bimodal cavity quantum electrodynamics

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    A scheme is proposed for generating entangled W states with four cavity modes. In this scheme, we send a Ⅴ-type three-level atom through two identical two-mode cavities in succession. After the atom exits from the second cavity,the four cavity modes are prepared in the W state. On the other hand we can obtain three-atom W states by sending three Ⅴ-type three-level atoms through a two-mode cavity in turn. The present scheme does not require conditional measurement, and it is easily generalized to preparing 2n-mode W states and n-atom W states.

  20. Theory and technology for superconducting cavities

    CERN Document Server

    Lengeler, Herbert

    1993-01-01

    The course will address Physicist and Engineers who are newcomers in the field of accelerators and accelerating cavities. The elements of RF-Superconductivity will be presented with special relevance to accelerating cavities. The present ststus of achievable accelerating fields and RF losses will be given and their link to the special technologies for cavity fabrication and surface treatments will be stressed. Cavity auxiliaries like main couplers, higher order mode couplers and frequency tuners will be described.

  1. Deflection of uncooperative targets using laser ablation

    Science.gov (United States)

    Thiry, Nicolas; Vasile, Massimiliano

    2015-09-01

    Owing to their ability to move a target in space without requiring propellant, laser-based deflection methods have gained attention among the research community in the recent years. With laser ablation, the vaporized material is used to push the target itself allowing for a significant reduction in the mass requirement for a space mission. Specifically, this paper addresses two important issues which are thought to limit seriously the potential efficiency of a laser-deflection method: the impact of the tumbling motion of the target as well as the impact of the finite thickness of the material ablated in the case of a space debris. In this paper, we developed a steady-state analytical model based on energetic considerations in order to predict the efficiency range theoretically allowed by a laser deflection system in absence of the two aforementioned issues. A numerical model was then implemented to solve the transient heat equation in presence of vaporization and melting and account for the tumbling rate of the target. This model was also translated to the case where the target is a space debris by considering material properties of an aluminium 6061-T6 alloy and adapting at every time-step the size of the computational domain along with the recession speed of the interface in order to account for the finite thickness of the debris component. The comparison between the numerical results and the analytical predictions allow us to draw interesting conclusions regarding the momentum coupling achievable by a given laser deflection system both for asteroids and space debris in function of the flux, the rotation rate of the target and its material properties. In the last section of this paper, we show how a reasonably small spacecraft could deflect a 56m asteroid with a laser system requiring less than 5kW of input power.

  2. accelerating cavity

    CERN Multimedia

    On the inside of the cavity there is a layer of niobium. Operating at 4.2 degrees above absolute zero, the niobium is superconducting and carries an accelerating field of 6 million volts per metre with negligible losses. Each cavity has a surface of 6 m2. The niobium layer is only 1.2 microns thick, ten times thinner than a hair. Such a large area had never been coated to such a high accuracy. A speck of dust could ruin the performance of the whole cavity so the work had to be done in an extremely clean environment.

  3. Crack deflection in brittle media with heterogeneous interfaces and its application in shale fracking

    Science.gov (United States)

    Zeng, Xiaguang; Wei, Yujie

    Driven by the rapid progress in exploiting unconventional energy resources such as shale gas, there is growing interest in hydraulic fracture of brittle yet heterogeneous shales. In particular, how hydraulic cracks interact with natural weak zones in sedimentary rocks to form permeable cracking networks is of significance in engineering practice. Such a process is typically influenced by crack deflection, material anisotropy, crack-surface friction, crustal stresses, and so on. In this work, we extend the He-Hutchinson theory (He and Hutchinson, 1989) to give the closed-form formulae of the strain energy release rate of a hydraulic crack with arbitrary angles with respect to the crustal stress. The critical conditions in which the hydraulic crack deflects into weak interfaces and exhibits a dependence on crack-surface friction and crustal stress anisotropy are given in explicit formulae. We reveal analytically that, with increasing pressure, hydraulic fracture in shales may sequentially undergo friction locking, mode II fracture, and mixed mode fracture. Mode II fracture dominates the hydraulic fracturing process and the impinging angle between the hydraulic crack and the weak interface is the determining factor that accounts for crack deflection; the lower friction coefficient between cracked planes and the greater crustal stress difference favor hydraulic fracturing. In addition to shale fracking, the analytical solution of crack deflection could be used in failure analysis of other brittle media.

  4. A single-mode external cavity diode laser using an intra-cavity atomic Faraday filter with short-term linewidth <400 kHz and long-term stability of <1 MHz

    Science.gov (United States)

    Keaveney, James; Hamlyn, William J.; Adams, Charles S.; Hughes, Ifan G.

    2016-09-01

    We report on the development of a diode laser system - the "Faraday laser" - using an atomic Faraday filter as the frequency-selective element. In contrast to typical external-cavity diode laser systems which offer tunable output frequency but require additional control systems in order to achieve a stable output frequency, our system only lases at a single frequency, set by the peak transmission frequency of the internal atomic Faraday filter. Our system has both short-term and long-term stability of less than 1 MHz, which is less than the natural linewidth of alkali-atomic D-lines, making similar systems suitable for use as a "turn-key" solution for laser-cooling experiments.

  5. A single-mode external cavity diode laser using an intra-cavity atomic Faraday filter with short-term linewidth $<400$ kHz and long-term stability of $<1$ MHz

    CERN Document Server

    Keaveney, James; Adams, Charles S; Hughes, Ifan G

    2016-01-01

    We report on the development of a diode laser system - the `Faraday laser' - using an atomic Faraday filter as the frequency-selective element. In contrast to typical external-cavity diode laser systems which offer tunable output frequency but require additional control systems in order to achieve a stable output frequency, our system only lases at a single frequency, set by the peak transmission frequency of the internal atomic Farady filter. Our system has both short-term and long-term stability of less than 1~MHz, which is less than the natural linewidth of alkali-atomic D-lines, making similar systems suitable for use as a `turn-key' solution for laser cooling experiments.

  6. A single-mode external cavity diode laser using an intra-cavity atomic Faraday filter with short-term linewidth <400 kHz and long-term stability of <1 MHz.

    Science.gov (United States)

    Keaveney, James; Hamlyn, William J; Adams, Charles S; Hughes, Ifan G

    2016-09-01

    We report on the development of a diode laser system - the "Faraday laser" - using an atomic Faraday filter as the frequency-selective element. In contrast to typical external-cavity diode laser systems which offer tunable output frequency but require additional control systems in order to achieve a stable output frequency, our system only lases at a single frequency, set by the peak transmission frequency of the internal atomic Faraday filter. Our system has both short-term and long-term stability of less than 1 MHz, which is less than the natural linewidth of alkali-atomic D-lines, making similar systems suitable for use as a "turn-key" solution for laser-cooling experiments.

  7. radiofrequency cavity

    CERN Multimedia

    1988-01-01

    The pulse of a particle accelerator. 128 of these radio frequency cavities were positioned around CERN's 27-kilometre LEP ring to accelerate electrons and positrons. The acceleration was produced by microwave electric oscillations at 352 MHz. The electrons and positrons were grouped into bunches, like beads on a string, and the copper sphere at the top stored the microwave energy between the passage of individual bunches. This made for valuable energy savings as it reduced the heat generated in the cavity.

  8. Feasibility study on a strain based deflection monitoring system for wind turbine blades

    Science.gov (United States)

    Lee, Kyunghyun; Aihara, Aya; Puntsagdash, Ganbayar; Kawaguchi, Takayuki; Sakamoto, Hiraku; Okuma, Masaaki

    2017-01-01

    The bending stiffness of the wind turbine blades has decreased due to the trend of wind turbine upsizing. Consequently, the risk of blades breakage by hitting the tower has increased. In order to prevent such incidents, this study proposes a deflection monitoring system that can be installed to already operating wind turbine's blades. The monitoring system is composed of an estimation algorithm to detect blade deflection and a wireless sensor network as a hardware equipment. As for the estimation method for blade deflection, a strain-based estimation algorithm and an objective function for optimal sensor arrangement are proposed. Strain-based estimation algorithm is using a linear correlation between strain and deflections, which can be expressed in a form of a transformation matrix. The objective function includes the terms of strain sensitivity and condition number of the transformation matrix between strain and deflection. In order to calculate the objective function, a simplified experimental model of the blade is constructed by interpolating the mode shape of a blade from modal testing. The interpolation method is effective considering a practical use to operating wind turbines' blades since it is not necessary to establish a finite element model of a blade. On the other hand, a sensor network with wireless connection with an open source hardware is developed. It is installed to a 300 W scale wind turbine and vibration of the blade on operation is investigated.

  9. Subwavelength rectangular cavity partially filled with left-handed materials

    Institute of Scientific and Technical Information of China (English)

    Jiang Tian; Chen Yan; Feng Yi-Jun

    2006-01-01

    In this paper, we present the electromagnetic analysis of a rectangular cavity partially filled with a left-handed material slab. Our theoretical investigation shows that there exist novel resonant modes in the cavity, and such a cavity becomes a subwavelength cavity. The eigenvalue equation of the cavity is derived and the resonant frequencies of the novel modes are calculated by using numerical simulation. We also discuss the stability of the novel resonant modes and show the best condition under which a useful rectangular cavity of subwavelength dimensions with tolerable stability is obtained.

  10. Wakefield Damping for the CLIC Crab Cavity

    Energy Technology Data Exchange (ETDEWEB)

    Ambattu, P.K.; Burt, G.; Dexter, A.C.; Carter, R.G.; /Cockcroft Inst. Accel. Sci. Tech. /Lancaster U.; Khan, V.; Jones, R.M.; /Cockcroft Inst. Accel. Sci. Tech. /Manchester U.; Dolgashev, V.; /SLAC

    2011-12-01

    A crab cavity is required in the CLIC to allow effective head-on collision of bunches at the IP. A high operating frequency is preferred as the deflection voltage required for a given rotation angle and the RF phase tolerance for a crab cavity are inversely proportional to the operating frequency. The short bunch spacing of the CLIC scheme and the high sensitivity of the crab cavity to dipole kicks demand very high damping of the inter-bunch wakes, the major contributor to the luminosity loss of colliding bunches. This paper investigates the nature of the wakefields in the CLIC crab cavity and the possibility of using various damping schemes to suppress them effectively.

  11. Study of surface charges in ballistic deflection transistors

    Science.gov (United States)

    Millithaler, J.-F.; Iñiguez-de-la-Torre, I.; Mateos, J.; GonzáIez, T.; Margala, M.

    2015-12-01

    This paper presents a comprehensive study of the behavior of surface charges in ballistic deflection transistors, at room temperature, where the in-plane geometry associating two drains with two gates in push-pull modes allows the control of electron path. Monte Carlo simulations were performed and compared with experimental data by using different models for accounting for surface charge effects. The simple model which assumes a constant and uniform value of the surface charge provides good results at equilibrium, but it is not able to correctly reproduce the BDT’s complex behavior when biased. We have confirmed that for a correct description of the device operation it is necessary to use a model allowing the surface charge to adapt itself locally to the carrier concentration in its surroundings.

  12. HOMs Simulation and Measurement Results of IHEP02 Cavity

    CERN Document Server

    Zheng, Hongjuan; Zhao, Tongxian; Gao, Jie

    2015-01-01

    In cavities, there exists not only the fundamental mode which is used to accelerate the beam but also higher order modes (HOMs). The higher order modes excited by beam can seriously affect beam quality, especially for the higher R/Q modes. This paper reports on measured results of higher order modes in the IHEP02 1.3GHz low-loss 9-cell superconducting cavity. Using different methods, Qe of the dangerous modes passbands have been got. The results are compared with TESLA cavity results. R/Q of the first three passbands have also been got by simulation and compared with the results of TESLA cavity.

  13. JLEIC SRF cavity RF Design

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Shaoheng [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Guo, Jiquan [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Wang, Haipeng [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Rimmer, Robert A. [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)

    2016-05-01

    The initial design of a low higher order modes (HOM) impedance superconducting RF (SRF) cavity is presented in this paper. The design of this SRF cavity is for the proposed Jefferson Lab Electron Ion Collider (JLEIC). The electron ring of JLEIC will operate with electrons of 3 to 10 GeV energy. The ion ring of JLEIC will operate with protons of up to 100 GeV energy. The bunch lengths in both rings are ~12 mm (RMS). In order to maintain the short bunch length in the ion ring, SRF cavities are adopted to provide large enough gradient. In the first phase of JLEIC, the PEP II RF cavities will be reused in the electron ring to lower the initial cost. The frequency of the SRF cavities is chosen to be the second harmonic of PEP II cavities, 952.6 MHz. In the second phase of JLEIC, the same frequency SRF cavities may replace the normal conducting PEP II cavities to achieve higher luminosity at high energy. At low energies, the synchro-tron radiation damping effect is quite weak, to avoid the coupled bunch instability caused by the intense closely-spaced electron bunches, low HOM impedance of the SRF cavities combined with longitudinal feedback sys-tem will be necessary.

  14. Nanofriction in Cavity Quantum Electrodynamics.

    Science.gov (United States)

    Fogarty, T; Cormick, C; Landa, H; Stojanović, Vladimir M; Demler, E; Morigi, Giovanna

    2015-12-01

    The dynamics of cold trapped ions in a high-finesse resonator results from the interplay between the long-range Coulomb repulsion and the cavity-induced interactions. The latter are due to multiple scatterings of laser photons inside the cavity and become relevant when the laser pump is sufficiently strong to overcome photon decay. We study the stationary states of ions coupled with a mode of a standing-wave cavity as a function of the cavity and laser parameters, when the typical length scales of the two self-organizing processes, Coulomb crystallization and photon-mediated interactions, are incommensurate. The dynamics are frustrated and in specific limiting cases can be cast in terms of the Frenkel-Kontorova model, which reproduces features of friction in one dimension. We numerically recover the sliding and pinned phases. For strong cavity nonlinearities, they are in general separated by bistable regions where superlubric and stick-slip dynamics coexist. The cavity, moreover, acts as a thermal reservoir and can cool the chain vibrations to temperatures controlled by the cavity parameters and by the ions' phase. These features are imprinted in the radiation emitted by the cavity, which is readily measurable in state-of-the-art setups of cavity quantum electrodynamics.

  15. Dark matter prospects in deflected mirage mediation

    Energy Technology Data Exchange (ETDEWEB)

    Holmes, Michael; Nelson, Brent D., E-mail: holmes.mi@neu.edu, E-mail: b.nelson@neu.edu [Department of Physics, Northeastern University, Boston, MA 02115 (United States)

    2009-07-01

    The recently introduced deflected mirage mediation (DMM) model is a string-motivated paradigm in which all three of the major supersymmetry-breaking transmission mechanisms are operative. We begin a systematic exploration of the parameter space of this rich model context, paying special attention to the pattern of gaugino masses which arise. In this work we focus on the dark matter phenomenology of the DMM model as such signals are the least influenced by the model-dependent scalar masses. We find that a large portion of the parameter space in which the three mediation mechanisms have a similar effective mass scale of 1 TeV or less will be probed by future direct and indirect detection experiments. Distinguishing deflected mirage mediation from the mirage model without gauge mediation will prove difficult without collider input, though we indicate how gamma ray signals may provide an opportunity for distinguishing between the two paradigms.

  16. Surface effects on large deflection of nanowires

    Institute of Scientific and Technical Information of China (English)

    杨帆

    2015-01-01

    Surface effects play an important role in the mechanical behavior of nanosized structural elements owing to the increased ratio of surface area to volume. The surface effects on the large deflection of nanowires were considered. Both geometric nonlinearity in finite deformation and surface effects at nanoscale were taken into account to analyze the bending of nanowires subjected to a concentrated force. For simply supported beams and clamped-clamped beams, the influence of surface effects and geometric nonlinearity were discussed in detail. It is found that both surface effects and geometric nonlinearity tend to decrease the deflection of bending nanowires and thus increase the effective elastic modulus of nanowires. Surface effects yield the size dependent behavior of nanowires.

  17. Optical forces through guided light deflections

    DEFF Research Database (Denmark)

    Palima, Darwin; Bañas, Andrew Rafael; Vizsnyiczai, Gaszton;

    2013-01-01

    Optical trapping and manipulation typically relies on shaping focused light to control the optical force, usually on spherical objects. However, one can also shape the object to control the light deflection arising from the light-matter interaction and, hence, achieve desired optomechanical effects....... In this work we look into the object shaping aspect and its potential for controlled optical manipulation. Using a simple bent waveguide as example, our numerical simulations show that the guided deflection of light efficiently converts incident light momentum into optical force with one order...... show that the force on the waveguide exceeds the combined forces on spherical trapping handles. Furthermore, it shows that static illumination can exert a constant force on a moving structure, unlike the position-dependent forces from harmonic potentials in conventional trapping....

  18. Deflection analysis of rectangular spatial coverage truss

    Directory of Open Access Journals (Sweden)

    M.N. Kirsanov

    2015-02-01

    Full Text Available An elastic spatial statically determinate truss of regular type, simulating the rectangular in plan coverage was considered. In the plane of the base the truss has two axes of symmetry. Four support structures (spherical hinge, cylindrical hinge and two vertical rods are located at its corners. An analytic solution was found for forces in the rods of the truss. Using the Maxwell-Mohr’s formula, the dependence of the deflection of the center was discovered in the truss under the influence of the concentrated force. There are five parameters of the problem in this formula: three linear dimensions, and the numbers of hinges on its lateral sides. To determine the desired patterns by means of the computer mathematics system Maple the recursion task by two parameters was solved. It was shown that dependence of the deflection on the number of panels and height of the truss detects a minimum, allowing optimizing the size of the structure.

  19. Cavity mode enhancement of terahertz emission from equilateral triangular microstrip antennas of the high-T c superconductor Bi2Sr2CaCu2O8 + δ

    Science.gov (United States)

    Cerkoney, Daniel P.; Reid, Candy; Doty, Constance M.; Gramajo, Ashley; Campbell, Tyler D.; Morales, Manuel A.; Delfanazari, Kaveh; Tsujimoto, Manabu; Kashiwagi, Takanari; Yamamoto, Takashi; Watanabe, Chiharu; Minami, Hidetoshi; Kadowaki, Kazuo; Klemm, Richard A.

    2017-01-01

    We study the transverse magnetic (TM) electromagnetic cavity mode wave functions for an ideal equilateral triangular microstrip antenna (MSA) exhibiting C 3v point group symmetry. When the C 3v operations are imposed upon the antenna, the TM(m,n) modes with wave vectors \\propto \\sqrt{{{m}2}+nm+{{n}2}} are much less dense than commonly thought. The R 3 operations restrict the integral n and m to satisfy |m-n| =3p , where p≥slant 0 and p≥slant 1 for the modes even and odd under reflections about the three mirror planes, respectively. We calculate the forms of representative wave functions and the angular dependence of the output power when these modes are excited by the uniform and non-uniform ac Josephson current sources in thin, ideally equilateral triangular MSAs employing the intrinsic Josephson junctions in the high transition temperature T c superconductor Bi2Sr2CaCu2 {{\\text{O}}8+δ} , and fit the emissions data from an earlier sample for which the C 3v symmetry was apparently broken.

  20. 带异形反射腔和寄生螺旋的均匀升角轴向模螺旋天线%Symmetrical pitch angle axial mode helical antennas with especial reflection cavity and parasitic helix

    Institute of Scientific and Technical Information of China (English)

    问建; 张割

    2012-01-01

    A helical antenna with a cuiving reflection cavity was designed based on symmetrical pitch angle axial mode helical antenna with a parasitic helix to improve radiation performance of axial mode helical antennas. Its radiation properties was simulated with the software HFSS. The contrast result come from the simulation of several helical antennas shows that the helical antenna can effectively improve the power gain coefficient of axial mode helical antenna. Its circular polarizable consistency is good. The method is simple and efficient for improving radiation performance of axial mode helical antennas.%为了改善轴向模螺旋天线的辐射特性,在带有寄生螺旋的均匀升角轴向模螺旋天线基础上,设计了一种带有曲反射面背腔的螺旋天线,并用HFSS软件对天线的辐射特性进行了仿真分析.通过对比几种不同形式的螺旋天线的仿真结果,证明了该种螺旋天线可以有效地提高轴向模螺旋天线增益系数,圆极化一致性良好,是一种提高轴向模螺旋天线性能的有效方法.

  1. Deflection of proton beams by crystal miscut surface

    CERN Document Server

    Babaev, A A; Dabagov, S B

    2014-01-01

    First computer experiment results on proton beam deflection by the crystal miscut surface are presented. The phenomenology of proton channeling and quasichanneling has been applied to describe new features of the beam deflection. The analysis predicts efficient beam deflection by the acute crystal end due to repelling miscut potential.

  2. Deflection rheoevolution of lithosphere under subduction

    Institute of Scientific and Technical Information of China (English)

    韩玉英; 王维襄

    1997-01-01

    Along the continental margin, the tectonic system consisting of trench, island arc, back arc basin and outer rise is often known as a convergent transitional belt between the oceanic lithosphere and the continental litho-sphere. The occurrence, development and activity of trench and outer rise bear closely on the underthrusting process of the oceanic lithosphere. A generalized analytical theory of deflection rheoevolution of lithosphere under subduction is established, and solutions with universal significance have been obtained.

  3. Long-cavity all-fiber ring laser actively mode locked with an in-fiber bandpass acousto-optic modulator.

    Science.gov (United States)

    Cuadrado-Laborde, C; Bello-Jiménez, M; Díez, A; Cruz, J L; Andrés, M V

    2014-01-01

    We demonstrate low-frequency active mode locking of an erbium-doped all-fiber ring laser. As the mode locker, we used a new in-fiber bandpass acousto-optic modulator showing 74% modulation depth, 3.7 dB power insertion losses, 4.5 nm of optical bandwidth, and 20 dB of nonresonant light suppression. The laser generates 330 ps mode-locked pulses over a 10 ns pedestal, at a 1.538 MHz frequency, with 130 mW of pump power.

  4. [Pliability and deflection of diagnostic catheters].

    Science.gov (United States)

    Pelyhe, Liza; Bognár, Eszter

    2014-09-28

    The cardiac catheter is an intravascular catheter, which is introduced or implanted into the heart for diagnostic or therapeutic reasons. The catheters may break or king during their introduction and/or removal. The aim of the authors was to study the pliability of two catheters with the same material but different diameters according to the Food and Drug Administration's recommendation. The bending points, diameter decrease, deflection, and their correlation and dependence on the distance from the tip, as well as the influence of the initial diameter of the catheters were determined. The bending of catheters was performed on 9 bending points (120-280 mm from the tip by 20 mm) on 16 gauges with different radius (10-2.5 mm by 0.5 mm). A linear dependency between the diameter decrease and deflection was observed, which was independent from the placement of the measurement in both catheters examined. The larger initial diameter had significant (p = 0.05) greater diameter decrease than the smaller, but the curves characteristic of the diameter decrease and deflection were similar. The applied method seems to be useful for the examination of weak points of cardiac catheters.

  5. Geometrically induced surface polaritons in planar nanostructured metallic cavities

    Energy Technology Data Exchange (ETDEWEB)

    Davids, P. S. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Intravia, F [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Dalvit, Diego A. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2014-01-14

    We examine the modal structure and dispersion of periodically nanostructured planar metallic cavities within the scattering matrix formulation. By nanostructuring a metallic grating in a planar cavity, artificial surface excitations or spoof plasmon modes are induced with dispersion determined by the periodicity and geometric characteristics of the grating. These spoof surface plasmon modes are shown to give rise to new cavity polaritonic modes at short mirror separations that modify the density of modes in nanostructured cavities. The increased modal density of states form cavity polarirons have a large impact on the fluctuation induced electromagnetic forces and enhanced hear transfer at short separations.

  6. Optomechanical photon shuttling between photonic cavities

    CERN Document Server

    Li, Huan

    2014-01-01

    Mechanical motion of photonic devices driven by optical forces provides a profound means of coupling between optical fields. The current focus of these optomechanical effects has been on cavity optomechanics systems in which co-localized optical and mechanical modes interact strongly to enable wave-mixing between photons and phonons and backaction cooling of mechanical modes. Alternatively, extended mechanical modes can also induce strong nonlocal effects on propagating optical fields or multiple localized optical modes at distances. Here, we demonstrate a novel multi-cavity optomechanical device: a "photon see-saw", in which torsional optomechanical motion can shuttle photons between two photonic crystal nanocavities. The resonance frequencies of the two cavities, one on each side of the see-saw, are modulated anti-symmetrically by the device's rotation. Pumping photons into one cavity excites optomechanical self-oscillation which strongly modulates the inter-cavity coupling and shuttles photons to the other...

  7. Optomechanical photon shuttling between photonic cavities.

    Science.gov (United States)

    Li, Huan; Li, Mo

    2014-11-01

    Mechanical motion of photonic devices driven by optical forces provides a profound means of coupling between optical fields. The current focus of these optomechanical effects has been on cavity optomechanics systems in which co-localized optical and mechanical modes interact strongly to enable wave mixing between photons and phonons, and backaction cooling of mechanical modes. Alternatively, extended mechanical modes can also induce strong non-local effects on propagating optical fields or multiple localized optical modes at distances. Here, we demonstrate a multicavity optomechanical device in which torsional optomechanical motion can shuttle photons between two photonic crystal nanocavities. The resonance frequencies of the two cavities, one on each side of this 'photon see-saw', are modulated antisymmetrically by the device's rotation. Pumping photons into one cavity excites optomechanical self-oscillation, which strongly modulates the inter-cavity coupling and shuttles photons to the other empty cavity during every oscillation cycle in a well-regulated fashion.

  8. Cryogenic Test of Double Quarter Wave Crab Cavity for the LHC High Luminosity Upgrade

    CERN Document Server

    Xiao, B; Belomestnykh, S; Ben-Zvi, I; Calaga, Rama; Cullen, C; Capatina, Ofelia; Hammons, L; Li, Z; Marques, C; Skaritka, J; Verdú-Andres, S; Wu, Q

    2015-01-01

    A Proof-of-Principle (PoP) Double Quarter Wave Crab Cavity (DQWCC) was designed and fabricated for the Large Hadron Collider (LHC) luminosity upgrade. A vertical cryogenic test has been done at Brookhaven National Lab (BNL). The cavity achieved 4.5 MV deflecting voltage with a quality factor above 3×109 . We report the test results of this design.

  9. 基于组合模理论设计的激光二极管阵列外腔%External Cavity Design for Laser Diode Bar Based on Calculation of Combined Array Mode

    Institute of Scientific and Technical Information of China (English)

    苏宙平; 朱焯炜; 阙立志

    2012-01-01

    针对激光二极管阵列提出了“组合模”慨念,计算了组合模的远场分布,每个组合模在远场的空间分布呈双瓣结构,基于激光二极管阵列组合模的远场分布特征,设计了离轴外腔反馈的激光二极管阵列,运用此装置所获得激光二极管阵列的远场分布有了明显变化,与自由运转的激光二极管阵列相比,离轴外腔反馈的激光二极管阵列远场宽度减少了4.3倍,在抽运电流为16 A时,测得输出激光的功率1.82W,这相当于相同电流下自由运转激光器输出功率的79%.组合模理论不仅可以用来指导设计一维离轴外腔反馈激光二极管阵列,而且也可以用于设计二维离轴外腔反馈激光二极管阵列.二维离轴外腔反馈激光二极管阵列可以产生高功率,高光束质量输出的激光.%In this paper,the concept of "combined array mode" for laser diode bar is proposcd.and the far-field profile of "combined array mode" is calculated.The far-field of each combined array mode exhibits a two-lobe profile with different angular position. On the basis of the characteristic of far-field profile of combined array mode,an off-axis external cavity feedback laser diode bar is designed. By employing the setup,the far-field profile of laser diode bar is narrowed by 4.3 times compared with the free- running laser diode bar. The output power of external cavity feedback laser diode bar is about 1.82 W at the drive current of 16 A.or 79% of the radiated power of the free-running state.The theory of combined array mode cannot only be applied to design the external cavity feedback laser diode har but also can be designed the external cavity feeedback laser diode stack.

  10. Finemet cavity impedance studies

    CERN Document Server

    Persichelli, S; Migliorati, M; Salvant, B

    2013-01-01

    The aim of the study is to evaluate the impedance of the Finemet kicker cavity to be installed in the PS straight section 02 during LS1, under realistic assumptions of bunch length. Time domain simulations with CST Particle Studio have been performed in order to get the impedance of the cavity and make a comparison with the longitudinal impedance measured for a single cell prototype. The study has been performed on simplified 3D geometries imported from a mechanical CATIA drawing, assuming that the simplications have small impact on the nal results. Simulations confirmed that the longitudinal impedance observed with measurements can be excited by bunches circulating in the PS. In the six-cells Finemet cavity, PS bunches circulating in the center can excite a longitudinal impedance, the real part of which has a maximum of 2 kOhm at 4 MHz. This mode does not seem to have any transverse component. All the eigenmodes of the cavity are strongly damped by the Finemet rings: we predict to have no issues regarding tr...

  11. The effect of a fiber reinforced cavity configuration on load bearing capacity and failure mode of endodontically treated molars restored with CAD/CAM resin composite overlay restorations

    NARCIS (Netherlands)

    Rocca, G.T.; Saratti, C.M.; Cattani-Lorente, M.; Feilzer, A.J.; Scherrer, S.; Krecji, I.

    2015-01-01

    Objectives To evaluate the fracture strength and the mode of failure of endodontically treated molars restored with CAD/CAM overlays with fiber reinforced composite build-up of the pulp chamber. Methods 40 Devitalized molars were cut over the CEJ and divided into five groups (n = 8). The pulp chambe

  12. Novel Geometries for the LHC CRAB Cavity

    CERN Document Server

    Hall, Ben

    2010-01-01

    In 2017 the LHC is envisioned to increase its luminosity via an upgrade. This upgrade is likely to require a large crossing angle hence a crab cavity is required to align the bunches prior to collision. There are two possible schemes for crab cavity implementation, global and local. In a global crab cavity the crab cavity is far from the IP and the bunch rotates back and forward as it traverses around the accelerator in a closed orbit. For this scheme a two-cell elliptical squashed cavity at 800 MHz is preferred. To avoid any potential beam instabilities all the parasitic modes of the cavities must be damped strongly, however crab cavities have lower order and same order modes in addition to the usual higher order modes and hence a novel damping scheme must be used to provide sufficient damping of these modes. In the local scheme two crab cavities are placed at each side of the IP two start and stop rotation of the bunches. This would require crab cavities much smaller transversely than in the global scheme b...

  13. Characterisation of a Mechanical Deflection Sensor

    CSIR Research Space (South Africa)

    Miyambo, M

    2012-10-01

    Full Text Available ). REFERENCES Snyman, I.M. and Reinecke, J.D. 2006. Measuring the impulse from an explosive charge, Ballistics Symposium South Africa, Denel-OTB, Bredasdorp, 15?16 Aug 2006. Miyambo, M.E. and Pandelani, T. 2012. The Mechanical Deflection Sensor Test... Mechanical Defl ection Sensor M MIYAMBO AND T PANDELANI CSIR Defence, Peace, Safety and Security, PO Box 395, Pretoria, South Africa, 0001 Email: mmiyambo@csir.co.za ? www.csir.co.za INTRODUCTION The CSIR Defence, Peace, Safety and Security (DPSS...

  14. Long term dynamics of the high luminosity Large Hadron Collider with crab cavities

    Science.gov (United States)

    Barranco García, J.; De Maria, R.; Grudiev, A.; Tomás García, R.; Appleby, R. B.; Brett, D. R.

    2016-10-01

    The High Luminosity upgrade of the Large Hadron Collider (HL-LHC) aims to achieve an integrated luminosity of 200 - 300 fb-1 per year, including the contribution from the upgrade of the injector chain. For the HL-LHC the larger crossing angle together with a smaller beta function at the collision point would result in more than 70% luminosity loss due to the incomplete geometric overlap of colliding bunches. To recover head-on collisions at the high-luminosity particle-physics detectors ATLAS and CMS and benefit from the very low β* provided by the Achromatic Telescopic Squeezing (ATS) optics, a local crab cavity scheme provides transverse kicks to the proton bunches. The tight space constraints at the location of these cavities leads to designs which are axially non-symmetric, giving rise to high order multipoles components of the main deflecting mode and, since these kicks are harmonic in time, we expand them in a series of multipoles in a similar fashion as is done for static field magnets. In this work we calculate, for the first time, the higher order multipoles and their impact on beam dynamics for three different crab cavity prototypes. Different approaches to calculate the multipoles are presented. Furthermore, we perform the first calculation of their impact on the long term stability of the machine using the concept of dynamic aperture.

  15. Three-qubit Fredkin gate based on cavity quantum electrodynamics

    Institute of Scientific and Technical Information of China (English)

    Shao Xiao-Qiang; Chen Li; Zhang Shou

    2009-01-01

    This paper presents a scheme for implementing a Fredkin gate on three modes of a cavity.The scheme is based on the dispersive atom-cavity interaction.By modulating the cavity frequency and the atomic transition frequency appropriately,it obtains the effective form of nonlinear interaction between photons in the three-mode cavity.This availability is testified via numerical analysis.It also considers both the situations with and without dissipation.

  16. A Bridge Deflection Monitoring System Based on CCD

    Directory of Open Access Journals (Sweden)

    Baohua Shan

    2016-01-01

    Full Text Available For long-term monitoring of the midspan deflection of Songjiazhuang cloverleaf junction on 309 national roads in Zibo city, this paper proposes Zhang’s calibration-based DIC deflection monitoring method. CCD cameras are used to track the change of targets’ position, Zhang’s calibration algorithm is introduced to acquire the intrinsic and extrinsic parameters of CCD cameras, and the DIC method is combined with Zhang’s calibration algorithm to measure bridge deflection. The comparative test between Zhang’s calibration and scale calibration is conducted in lab, and experimental results indicate that the proposed method has higher precision. According to the deflection monitoring scheme, the deflection monitoring software for Songjiazhuang cloverleaf junction is developed by MATLAB, and a 4-channel CCD deflection monitoring system for Songjiazhuang cloverleaf junction is integrated in this paper. This deflection monitoring system includes functions such as image preview, simultaneous collection, camera calibration, deflection display, and data storage. In situ deflection curves show a consistent trend; this suggests that the proposed method is reliable and is suitable for the long-term monitoring of bridge deflection.

  17. Energy Levels of Coupled Plasmonic Cavities

    Institute of Scientific and Technical Information of China (English)

    Chuan-Pu Liu; Xin-Li Zhu; Jia-Sen Zhang; Jun Xu; Yamin Leprince-Wang; Da-Peng Yu

    2016-01-01

    We demonstrate the hybridization of the plasmonic modes in directly coupled whispering gallery cavities fabricated on silver films and present the mode patterns and energy levels using cathodoluminescence spectroscopy.Although the energy of the most antisymmetrically coupled modes is higher than that of the corresponding symmetrically coupled ones,the contrary cases happen for small quantum number modes.We attribute the phenomenon to the different surface plasmon polariton paths between the symmetrically and antisymmetrically coupled modes.These results provide an understanding of the resonant properties in coupled plasmonic cavities,which have potential applications in nanophotonic devices.

  18. Entanglement distillation for atomic states via cavity QED

    Science.gov (United States)

    Yang, Ming; Song, Wei; Cao, Zhuo-Liang

    2004-10-01

    Following a recent proposal (Phys. Rev. Lett. 85 (2000) 2392) about quantum information processing using dispersive atom-cavity interaction, in this paper, we proposed a physical scheme to concentrate the pure non-maximally entangled atomic states via cavity QED by using atomic collision in a far-off-resonant cavity. The most distinctive advantage of our scheme is that there is no excitation of cavity mode during the distillation procedure. Therefore the requirement on the quality of cavity is greatly loosened.

  19. Unconventional geometric quantum phase gates with a cavity QED system

    Science.gov (United States)

    Zheng, Shi-Biao

    2004-11-01

    We propose a scheme for realizing two-qubit quantum phase gates via an unconventional geometric phase shift with atoms in a cavity. In the scheme the atoms interact simultaneously with a highly detuned cavity mode and a classical field. The atoms undergo no transitions during the gate operation, while the cavity mode is displaced along a circle in the phase space, aquiring a geometric phase conditional upon the atomic state. Under certain conditions, the atoms are disentangled with the cavity mode and thus the gate is insensitive to both the atomic spontaneous emission and the cavity decay.

  20. Experimental and numerical study on vibrations and static deflection of a thin hyperelastic plate

    Science.gov (United States)

    Amabili, Marco; Balasubramanian, Prabakaran; Breslavsky, Ivan D.; Ferrari, Giovanni; Garziera, Rinaldo; Riabova, Kseniia

    2016-12-01

    The hyperelastic behavior of a thin square silicone rubber plate has been investigated analytically, numerically and experimentally; the case of small-amplitude vibrations has been considered, as well as the case of large static deflection under aerostatic pressure. The Mooney-Rivlin hyperelastic model has been chosen to describe the material nonlinear elasticity. The material parameters have been identified by a fitting procedure on the results of a uniaxial traction test. For the analytical model, the equations of motion have been obtained by a unified energy approach, and geometrical nonlinearities are modeled according to the Novozhilov nonlinear shell theory. A numerical model has also been developed by using a commercial Finite-Element code. In the experiments, the silicone rubber plate has been fixed to a heavy metal frame; a certain in-plane pre-load, applied by stretching the plate, has been given in order to ensure a flatness of the surface. An experimental modal analysis has been conducted; results have been used to identify the applied in-plane loads by optimization procedure with two different models: a numerical and an analytical one. The first four experimental and numerical natural modes and frequencies are in good agreement with the experiments after the pre-load identification. The static deflection has been measured experimentally for different pressures. Results have been compared to those obtained by analytical and numerical models. The static deflections are also satisfactorily compared, up to a deflection 50 times larger than the plate thickness, corresponding to a 30 percent strain.

  1. Mode selection laser

    DEFF Research Database (Denmark)

    2014-01-01

    The invention relates to a semiconductor mode selection laser, particularly to a VCSEL laser (200) having mode selection properties. The mode selection capability of the laser is achieved by configuring one of the reflectors (15,51) in the resonance cavity so that a reflectivity of the reflector...... (15) varies spatially in one dimension or two dimensions. Accordingly, the reflector (15) with spatially varying reflectivity is part both of the resonance cavity and the mode selection functionality of the laser. A plurality of the lasers configured with different mode selectors, i.e. different...... spatial reflector variations, may be combined to generate a laser beam containing a plurality of orthogonal modes. The laser beam may be injected into a few- mode optical fiber, e.g. for the purpose of optical communication. The VCSEL may have intra-cavity contacts (31,37) and a Tunnel junction (33...

  2. A Limited Deflection Routing Algorithm Based on Burst Loss Threshold in OBS Networks

    Institute of Scientific and Technical Information of China (English)

    WANG Ru-yan; LONG Ke-ping; WU Wei; YANG Xiao-long; ZHU Wei-le

    2005-01-01

    The deflection routing protocol is an effective contention resolution in Optical Burst Switching network. However, it can worsen loss performance of non-deflected burst on the deflection route. To improve the burst loss performance, a limited deflection routing scheme based on burst loss threshold is proposed to prevent injudicious deflection routing. By using threshold check function, it restrainedly allows the deflected burst to preemptive network resource, consequently, improve the QoS performance of non-deflected burst. Simulation results show that the scheme can efficiently prevent deflected burst contending with non-deflected burst on deflection route, and effectively improve the burst loss performance of entire networks.

  3. Deflections of Nanowires with Consideration of Surface Effects

    Institute of Scientific and Technical Information of China (English)

    LI He; YANG Zhou; ZHANG Yi-Min; WEN Bang-Chun

    2010-01-01

    @@ The elementary beam model is modified to include the surface effects and used to analyze the deflections of nanowires under different boundary conditions.The results show that compared to deflections of nanowires without consideration of surface effects,the surface effects can enlarge or reduce deflections of nanowires,and nanowire buckling occurs under certaJn conditions.This study might be helpful for design of nanowire-based nanoelectromechanical systems.

  4. Coupled Resonator Vertical Cavity Laser Diode

    Energy Technology Data Exchange (ETDEWEB)

    CHOQUETTE, KENT D.; CHOW, WENG W.; FISCHER, ARTHUR J.; GEIB, KENT M.; HOU, HONG Q.

    1999-09-16

    We report the operation of an electrically injected monolithic coupled resonator vertical cavity laser which consists of an active cavity containing In{sub x}Ga{sub 1{minus}x}As quantum wells optically coupled to a passive GaAs cavity. This device demonstrates novel modulation characteristics arising from dynamic changes in the coupling between the active and passive cavities. A composite mode theory is used to model the output modulation of the coupled resonator vertical cavity laser. It is shown that the laser intensity can be modulated by either forward or reverse biasing the passive cavity. Under forward biasing, the modulation is due to carrier induced changes in the refractive index, while for reverse bias operation the modulation is caused by field dependent cavity enhanced absorption.

  5. CHECHIA cavity driving with FPGA controller

    Energy Technology Data Exchange (ETDEWEB)

    Czarski, T.; Koprek, W.; Pozniak, K.T.; Romaniuk, R.S. [Technical Univ. Warsaw (Poland). ELHEP Laboratory, ISE; Simrock, S. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany). TESLA

    2005-07-01

    The initial control of the superconductive cavity has recently been performed by applying the FPGA (Field Programmable Gate Array) technology system in DESY Hamburg. This first experiment turned attention to the general recognition of the cavity features and projected control methods. The electrical model of the cavity is taken as a consideration origin. The calibration of the signal channel is considered as a key preparation for an efficient cavity driving. The cavity parameters identification is confirmed as a proper approach for the required performance: driving on resonance during filling and field stabilization during flattop time with reasonable power consumption. The feed-forward and feedback modes were applied successfully for the CHECHIA cavity driving. Representative results of experiments are presented for different levels of the cavity field gradient. (orig.)

  6. Deflection of elastic beam with SMA wires eccentrically inserted

    Science.gov (United States)

    Jamian, S.; Nik Mohamed, N. A.; Ihsan, A. K. A. Mohd; Ismail, A. E.; Nor, M. K. Mohd; Kamarudin, K. A.; Nor, N. H. Muhd

    2017-08-01

    This research is intended to investigate the ability of shape memory alloys (SMA), through its activation, in generating loads to control beam deflection. An elastic beam is formed by sandwiching eccentrically SMA wires between two elastic plates. SMA wires are activated by electrical current from the power supply. Laser displacement meter (LDM) is used to measures deflection of sample. Results show that the deflection of the beam is dependent on the temperature change. The temperature-deflection response also shows the existence of hysteresis.

  7. Photon deflection by a Coulomb field in noncommutative QED

    Energy Technology Data Exchange (ETDEWEB)

    Pires, C A de S [Departamento de FIsica, Universidade Federal da ParaIba, Caixa Postal 5008, 58059-970, Joao Pessoa, PB (Brazil)

    2004-12-01

    In noncommutative QED photons present self-interactions in the form of triple and quartic interactions. The triple interaction implies that, even though the photon is electrically neutral, it will deflect when in the presence of an electromagnetic field. If detected, such deflection would be undoubted evidence of noncommutative space-time. In this work we derive a general expression for the deflection of a photon by any electromagnetic field. As an application we consider the case of the deflection of a photon by an external static Coulomb field. (brief report)

  8. Photon deflection by a Coulomb field in noncommutative QED

    CERN Document Server

    De Pires, C A S

    2004-01-01

    In noncommutative QED photons present self-interactions in the form of triple and quartic interactions. The triple interaction implies that, even though the photon is electrically neutral, it will deflect when in the presence of an electromagnetic field. If detected, such deflection would be an undoubted signal of noncommutative space-time. In this work we derive the general expression for the deflection of a photon by any electromagnetic field. As an application we consider the case of the deflection of a photon by an external static Coulomb field.

  9. Temperature stabilization of optofluidic photonic crystal cavities

    DEFF Research Database (Denmark)

    Kamutsch, Christian; Smith, Cameron L.C.; Graham, Alexandra;

    2009-01-01

    We present a principle for the temperature stabilization of photonic crystal (PhC) cavities based on optofluidics. We introduce an analytic method enabling a specific mode of a cavity to be made wavelength insensitive to changes in ambient temperature. Using this analysis, we experimentally demon...

  10. Cavity Optomechanical Magnetometer

    CERN Document Server

    Forstner, S; Knittel, J; van Ooijen, E D; Swaim, J D; Harris, G I; Szorkovszky, A; Bowen, W P; Rubinsztein-Dunlop, H

    2011-01-01

    A cavity optomechanical magnetometer is demonstrated where the magnetic field induced expansion of a magnetostrictive material is transduced onto the physical structure of a highly compliant optical microresonator. The resulting motion is read out optically with ultra-high sensitivity. Detecting the magnetostrictive deformation of Terfenol-D with a toroidal whispering gallery mode (TWGM) resonator a peak sensitivity of 400 nT/Hz^.5 was achieved with theoretical modelling predicting that sensitivities of up to 500 fT/Hz^.5 may be possible. This chip-based magnetometer combines high-sensitivity and large dynamic range with small size and room temperature operation.

  11. Droplet based cavities and lasers

    DEFF Research Database (Denmark)

    Mølhave, Kristian; Kristensen, Anders; Mortensen, Asger

    2009-01-01

    The self-organized and molecularly smooth surface on liquid microdroplets makes them attractive as optical cavities with very high quality factors. This chapter describes the basic theory of optical modes in spherical droplets. The mechanical properties including vibrational excitation are also d...

  12. Linearized gravity, Newtonian limit and light deflection in RS1 model

    CERN Document Server

    Smolyakov, M N; Smolyakov, Mikhail N.; Volobuev, Igor P.

    2002-01-01

    We solve exactly the equations of motion for linearized gravity in the Randall-Sundrum model with matter on the branes and calculate the Newtonian limit in it. The result contains contributions of the radion and of the massive modes, which change considerably Newton's law at small distances. The effects of "shadow" matter, which lives on the other brane, are considered and compared with those of ordinary matter for both positive and negative tension branes. We also calculate light deflection and Newton's law in the zero mode approximation and explicitly distinguish the contribution of the radion field.

  13. The CEBAF Separator Cavity Resonance Control System

    CERN Document Server

    Wissmann, Mark J; Hovater, Curt; Plawski, Tomasz

    2005-01-01

    The CEBAF energy upgrade from 6 GeV to 12GeV will increase the range of beam energies available to the experimental halls. RF deflection cavities (separators) are used to direct the electron beam to the three experimental halls. Consequently with the increase in RF separator cavity gradient needed for the higher energies, RF power will also increase requiring the cavities to have active resonance control. At the 6 GeV energy, the cavities are tuned mechanically and then stabilized with Low Conductivity Water (LCW), which is maintained at constant temperature of 95o Fahrenheit. This is no longer feasible and an active resonance control system, that controls both water temperature and flow has been built. The system uses a commercial PLC with embedded PID controls to control water temperature and flow to the cavities. The system allows the operator to remotely adjust temperature/flow and consequently cavity resonance for the full range of beam energies. Ultimately closed loop control will be maintained by monit...

  14. Chaotic dynamics of a classical radiant cavity

    CERN Document Server

    Benenti, G; Guarneri, I; Benenti, Giuliano; Casati, Giulio; Guarneri, Italo

    1999-01-01

    The statistical properties of a classical electromagnetic field in interaction with matter are numerically investigated on a one-dimensional model of a radiant cavity, conservative and with finite total energy. Our results suggest a trend towards equipartition of energy, with the relaxation times of the normal modes of the cavity increasing with the mode frequency according to a law, the form of which depends on the shape of the charge distribution.

  15. Electrically Pumped Vertical-Cavity Amplifiers

    DEFF Research Database (Denmark)

    Greibe, Tine

    2007-01-01

    In this work, the design of electrically pumped vertical cavity semiconductor optical amplifiers (eVCAs) for use in a mode-locked external-cavity laser has been developed, investigated and analysed. Four different eVCAs, one top-emitting and three bottom emitting structures, have been designed...... and discussed. The thesis concludes with recommendations for further work towards the realisation of compact electrically pumped mode-locked vertical externalcavity surface emitting lasers....

  16. Teach Deflection Concepts with Hacksaw Blades and Rubber Bands

    Science.gov (United States)

    Roman, Harry T.

    2013-01-01

    Technology and engineering educators can use a simple hacksaw blade to help students learn about deflection, as that which occurs in a beam. Here the beam is fixed at one end and allowed to deflect in a manner that is easy to see and measure--the hacksaw blade represents a cantilever, an overhanging structure. This simple and very inexpensive…

  17. State of the Art SRF Cavity Performance

    CERN Document Server

    Lilje, L

    2004-01-01

    The paper will review superconducting RF cavity performance for β=1 cavities used in both linear and circular accelerators. These superconducting cavities are used in two kinds of applications: High current storage rings and efficient high duty cycle linacs. In recent years the performance of those cavities has been improving steadily. High accelerating gradients have been achieved using advanced surface preparation techniques like electropolishing and surface cleaning methods like high pressure water rinsing. High intensity beams can be handled with advanced higher-order-mode damping schemes.

  18. Clustering mechanism of ethanol-water mixtures investigated with photothermal microfluidic cantilever deflection spectroscopy

    Science.gov (United States)

    Ghoraishi, M. S.; Hawk, J. E.; Phani, Arindam; Khan, M. F.; Thundat, T.

    2016-04-01

    The infrared-active (IR) vibrational mode of ethanol (EtOH) associated with the asymmetrical stretching of the C-C-O bond in pico-liter volumes of EtOH-water binary mixtures is calorimetrically measured using photothermal microfluidic cantilever deflection spectroscopy (PMCDS). IR absorption by the confined liquid results in wavelength dependent cantilever deflections, thus providing a complementary response to IR absorption revealing a complex dipole moment dependence on mixture concentration. Solvent-induced blue shifts of the C-C-O asymmetric vibrational stretch for both anti and gauche conformers of EtOH were precisely monitored for EtOH concentrations ranging from 20–100% w/w. Variations in IR absorption peak maxima show an inverse dependence on induced EtOH dipole moment (μ) and is attributed to the complex clustering mechanism of EtOH-water mixtures.

  19. Monitoring electrostatically-induced deflection, strain and doping in suspended graphene using Raman spectroscopy

    Science.gov (United States)

    Metten, Dominik; Froehlicher, Guillaume; Berciaud, Stéphane

    2017-03-01

    Electrostatic gating offers elegant ways to simultaneously strain and dope atomically thin membranes. Here, we report on a detailed in situ Raman scattering study on graphene, suspended over a Si/SiO2 substrate. In such a layered structure, the intensity of the Raman G- and 2D-mode features of graphene are strongly modulated by optical interference effects and allow an accurate determination of the electrostatically-induced membrane deflection, up to irreversible collapse. The membrane deflection is successfully described by an electromechanical model, which we also use to provide useful guidelines for device engineering. In addition, electrostatically-induced tensile strain is determined by examining the softening of the Raman features. Due to a small residual charge inhomogeneity, we find that non-adiabatic anomalous phonon softening is negligible compared to strain-induced phonon softening. These results open perspectives for innovative Raman scattering-based readout schemes in two-dimensional nanoresonators.

  20. Quasi first-order Hermite Gaussian beam for enhanced sensitivity in Sagnac interferometer photothermal deflection spectroscopy.

    Science.gov (United States)

    Shiokawa, Naoyuki; Tokunaga, Eiji

    2016-05-30

    The detection sensitivity of a Sagnac interferometer photothermal deflection spectroscopy was enhanced by changing the probe beam pattern from zero-order to a quasi-first-order Hermite Gaussian (QHG) beam. The nature of the higher order HG mode, where the beam pattern is preserved during propagation with an increased field gradient, is utilized to enhance the measurement sensitivity. In this spectroscopy, the lateral beam deflection due to the photothermal effect is sensitively detected as a change in the interference light intensity. The change in intensity is amplified due to the higher field gradient of the QHG(1,0) beam at the photodetector. This amplification effect was both numerically and experimentally demonstrated to obtain twofold improvement in the signal-to-noise ratio.

  1. A numerical analysis of the influence of the cavitator’s deflection angle on flow features for a free moving supercavitated vehicle

    Institute of Scientific and Technical Information of China (English)

    陈鑫; 鲁传敬; 陈瑛; 曹嘉怡

    2014-01-01

    When a high-speed cavitated weapon moves under water, the flow properties are important issues for the sake of the trajectory predication and control. In this paper, a single-fluid multiphase flow method coupled with a natural cavitation model is proposed to numerically simulate the free moving phase of an underwater supercavitated vehicle under the action of the external thrust. The influence of the cavitator’s deflection angle ranging fromo-3 to3o on the cavity pattern, the hydrodynamics and the underwater trajectory is investigated. Based on computational results, several conclusions are qualitatively drawn by an analysis. The deflection angle has very little effect on the cavity pattern. When the deflection angle increases, the variation curves of the vertical linear velocity, the lift coefficient and the pitching moment coefficient become flatter. In the phase of the second natural cavitation, at a same time, the greater the deflection angle is, the lower the drag and the lift coefficients will be and the higher the pitching moment coefficient becomes. At the finishing time of the free moving phase, when the deflection angle lies in the small range ofoo-1-1, the position of the center of mass and the pitching angle of the vehicle are more close to each other. However, when the deflection angle is less thano-1 or greater than1o, the position of the center of mass and the pitching angle change greatly. If a proper deflection angle of the cavitator is adopted, the underwater vehicle can navigate in a pseudo-fixed depth.

  2. Study on the causes and methods of influencing concrete deflection

    Science.gov (United States)

    Zhou, Ying; Zhou, Xiang; Tang, Jinyu

    2017-09-01

    Under the long-term effect of static load on reinforced concrete beam, the stiffness decreases and the deformation increases with time. Therefore, the calculation of deflection is more complicated. According to the domestic and foreign research results by experiment the flexural deflection of reinforced concrete, creep, age, the thickness of the protective layer, the relative slip, the combination of steel yielding factors of reinforced concrete deflection are summarized, analyzed the advantages and disadvantages of the traditional direct measurement of deflection, that by increasing the beam height, increasing the moment of inertia, ncrease prestressed reinforcement ratio, arching, reduce the load, and other measures to reduce the deflection of prestressed construction, improve the reliability of structure.

  3. Impacts of Deflection Nose on Ballistic Trajectory Control Law

    Directory of Open Access Journals (Sweden)

    Bo Zhang

    2014-01-01

    Full Text Available The deflection of projectile nose is aimed at changing the motion of the projectile in flight with the theory of motion control and changing the exterior ballistics so as to change its range and increase its accuracy. The law of external ballistics with the deflectable nose is considered as the basis of the design of a flight control system and an important part in the process of projectile development. Based on the existing rigid external ballistic model, this paper establishes an external ballistic calculation model for deflectable nose projectile and further establishes the solving programs accordingly. Different angle of attack, velocity, coefficients of lift, resistance, and moment under the deflection can be obtained in this paper based on the previous experiments and emulation researches. In the end, the author pointed out the laws on the impaction of external ballistic trajectory by the deflection of nose of the missile.

  4. Modeling and Simulating Dynamics of Missiles with Deflectable Nose Control

    Institute of Scientific and Technical Information of China (English)

    Gao Yuan; Gu Liangxian; Pan Lei

    2009-01-01

    This article investigates the dynamic characteristics of deflectable nose missiles with rotary single-channel control. After introduction of effective attack and sideslip angles as well as quasi-body coordinates based on the spin characteristics of the missile's body, an integrated rigid kinetic model of missile with deflectable nose control is set up in the quasi-body coordinates considering the interaction between the missile's nose and body by using rootless multi-rigid-body system dynamics and is linearized. Then an analysis with simulation is conducted to investigate the coupling characteristics between the channels, the influences of nose deflection on the body and the dynamic characteristics of missile's body. The results indicate that various channels of missiles with deflectable nose control are coupled cross-linked; the nose deflection tends to make the body move in the opposite direction and, finally, evidences the correctness and reasonability of the kinetic model proposed by this article.

  5. AIDA: the Asteroid Impact & Deflection Assessment mission

    Science.gov (United States)

    Vincent, Jean-Baptiste

    2016-07-01

    The Asteroid Impact & Deflection Assessment (AIDA) mission is a joint cooperation between European and US space agencies that consists of two separate and independent spacecraft that will be launched to a binary asteroid system, the near-Earth asteroid Didymos, to assess the possibility of deflecting an asteroid trajectory by using a kinetic impactor. The European Asteroid Impact Mission (AIM) is under Phase A/B1 study at ESA from March 2015 until summer 2016. AIM is set to rendez-vous with the asteroid system a few months prior to the impact by the US Double Asteroid Redirection Test (DART) spacecraft to fully characterize the smaller of the two binary components. AIM is a unique mission as it will be the first time that a spacecraft will investigate the surface, subsurface, and internal properties of a small binary near Earth asteroid. In addition it will perform various important technology demonstrations that can serve other space missions: AIM will release a set of CubeSats in deep space and a lander on the surface of the smaller asteroid and for the first time, deep-space inter-satellite linking will be demonstrated between the main spacecraft, the CubeSats, and the lander, and data will also be transmitted from interplanetary space to Earth by a laser communication system. The knowledge obtained by this mission will have great implications for our understanding of the history of the Solar System. Small asteroids are believed to result from collisions and other processes (e.g., spinup, shaking) that made them what they are now. Having direct information on their surface and internal properties will allow us to understand how these processes work and transform these small bodies as well as, for this particular case, how a binary system forms. So far, our understanding of the collisional process and the validation of numerical simulations of the impact process rely on impact experiments at laboratory scales. With DART, thanks to the characterization of the

  6. TESLA superconducting RF cavity development

    Energy Technology Data Exchange (ETDEWEB)

    Koepke, K. [Fermi National Accelerator Lab., Batavia, IL (United States); TESLA Collaboration

    1995-05-01

    The TESLA collaboration has made steady progress since its first official meeting at Cornell in 1990. The infrastructure necessary to assemble and test superconducting rf cavities has been installed at the TESLA Test Facility (TTF) at DESY. 5-cell, 1.3 GHz cavities have been fabricated and have reached accelerating fields of 25 MV/m. Full sized 9-cell copper cavities of TESLA geometry have been measured to verify the higher order modes present and to evaluate HOM coupling designs. The design of the TESLA 9-cell cavity has been finalized and industry has started delivery. Two prototype 9-cell niobium cavities in their first tests have reached accelerating fields of 10 MV/m and 15 MV/m in a vertical dewar after high peak power (HPP) conditioning. The first 12 m TESLA cryomodule that will house 8 9-cell cavities is scheduled to be delivered in Spring 1995. A design report for the TTF is in progress. The TTF test linac is scheduled to be commissioned in 1996/1997. (orig.).

  7. Coupled Resonator Vertical Cavity Laser Diodes

    Energy Technology Data Exchange (ETDEWEB)

    Choquette, K.D.; Chow, W.W.; Fischer, A.J.; Allerman, A.A.; Hou, H.Q.; Geib, K.M.

    1999-07-22

    For many applications, the device performance of edge emitting semiconductor lasers can be significantly improved through the use of multiple section devices. For example, cleaved coupled cavity (C3) lasers have been shown to provide single mode operation, wavelength tuning, high speed switching, as well as the generation of short pulses via mode-locking and Q-switching [1]. Using composite resonators within a vertical cavity laser opens up new possibilities due to the unique ability to tailor the coupling between the monolithic cavities, incorporate passive or active resonators which are spectrally degenerate or detuned, and to fabricate these devices in 2-dimensional arrays. Composite resonator vertical cavity lasers (CRVCL) have been examined using optical pumping and electrical injection [2-5]. We report on CRVCL diodes and show that efficient modulation of the laser emission can be achieved by either forward or reverse biasing the passive cavity within a CRVCL.

  8. Load Deflection Characteristics of Nickel Titanium Initial Archwires

    Directory of Open Access Journals (Sweden)

    Hossein Aghili

    2016-05-01

    Full Text Available Objectives: The aim of this study was to assess and compare the characteristics of commonly used initial archwires by their load deflection graphs.Materials and Methods: This study tested three wire designs namely copper nickel titanium (CNT, nickel titanium (NiTi, and multi-strand NiTi (MSNT archwires engaged in passive self-ligating (PSL brackets, active self-ligating (ASL brackets or conventional brackets. To evaluate the mechanical characteristics of the specimens, a three-point bending test was performed. The testing machine vertically applied force on the midpoint of the wire between the central incisor and canine teeth to obtain 2 and 4mm of deflection. The force level at maximum deflection and characteristics of plateau (the average plateau load and the plateau length were recorded. Two-way ANOVA and Tukey’s test were used at P <0.05 level of significance.Results: Force level at maximum deflection and plateau length were significantly affected by the amount of deflection. The type of archwires and brackets had significant effects on force level at maximum deflection, and plateau length. However, the bracket type had no significant effect on the average plateau force.Conclusion: With any type of brackets in deflections of 2 and 4mm, MSNT wire exerted the lowest while NiTi wire exerted the highest force level at maximum deflection and plateau phase. The force level at maximum deflection and the plateau length increased with raising the amount of primary deflection; however the average plateau force did not change significantly.

  9. Optimized frequency dependent photothermal beam deflection spectroscopy

    Science.gov (United States)

    Korte, D.; Cabrera, H.; Toro, J.; Grima, P.; Leal, C.; Villabona, A.; Franko, M.

    2016-12-01

    In the letter the optimization of the experimental setup for photothermal beam deflection spectroscopy is performed by analyzing the influence of its geometrical parameters (detector and sample position, probe beam radius and its waist position etc) on the detected signal. Furthermore, the effects of the fluid’s thermo-optical properties, for optimized geometrical configuration, on the measurement sensitivity and uncertainty determination of sample thermal properties is also studied. The examined sample is a recently developed CuFeInTe3 material. It is seen from the obtained results, that it is a complex problem to choose the proper geometrical configuration as well as sensing fluid to enhance the sensitivity of the method. A signal enhancement is observed at low modulation frequencies by placing the sample in acetonitrile (ACN), while at high modulation frequencies the sensitivity is higher for measurements made in air. For both, detection in air and acetonitrile the determination of CuFeInTe3 thermal properties is performed. The determined values of thermal diffusivity and thermal conductivity are (0.048  ±  0.002)  ×  10-4 m2 s-1 and 4.6  ±  0.2 W m-1 K-1 and (0.056  ±  0.005)  ×  10-4 m2 s-1 and 4.8  ±  0.4 W m-1 K-1 for ACN and air, respectively. It is seen, that the determined values agree well within the range of their measurement uncertainties for both cases, although the measurement uncertainty is two times lower for the measurements in ACN providing more accurate results. The analysis is performed by the use of recently developed theoretical description based on the complex geometrical optics. It is also shown, how the presented work fits into the current status of photothermal beam deflection spectroscopy.

  10. Perturbing Open Cavities: Anomalous Resonance Frequency Shifts in a Hybrid Cavity-Nanoantenna System

    Science.gov (United States)

    Ruesink, Freek; Doeleman, Hugo M.; Hendrikx, Ruud; Koenderink, A. Femius; Verhagen, Ewold

    2015-11-01

    The influence of a small perturbation on a cavity mode plays an important role in fields like optical sensing, cavity quantum electrodynamics, and cavity optomechanics. Typically, the resulting cavity frequency shift directly relates to the polarizability of the perturbation. Here, we demonstrate that particles perturbing a radiating cavity can induce strong frequency shifts that are opposite to, and even exceed, the effects based on the particles' polarizability. A full electrodynamic theory reveals that these anomalous results rely on a nontrivial phase relation between cavity and nanoparticle radiation, allowing backaction via the radiation continuum. In addition, an intuitive model based on coupled mode theory is presented that relates the phenomenon to retardation. Because of the ubiquity of dissipation, we expect these findings to benefit the understanding and engineering of a wide class of systems.

  11. Perturbing open cavities: Anomalous resonance frequency shifts in a hybrid cavity-nanoantenna system

    CERN Document Server

    Ruesink, Freek; Hendrikx, Ruud; Koenderink, A Femius; Verhagen, Ewold

    2015-01-01

    The influence of a small perturbation on a cavity mode plays an important role in fields like optical sensing, cavity quantum electrodynamics and cavity optomechanics. Typically, the resulting cavity frequency shift directly relates to the polarizability of the perturbation. Here we demonstrate that particles perturbing a radiating cavity can induce strong frequency shifts that are opposite to, and even exceed, the effects based on the particles' polarizability. A full electrodynamic theory reveals that these anomalous results rely on a non-trivial phase relation between cavity and nanoparticle radiation, allowing back-action via the radiation continuum. In addition, an intuitive model based on coupled mode theory is presented that relates the phenomenon to retardation. Because of the ubiquity of dissipation, we expect these findings to benefit the understanding and engineering of a wide class of systems.

  12. Bound Modes in Dielectric Microcavities

    CERN Document Server

    Visser, P M; Lenstra, D

    2002-01-01

    We demonstrate how exactly bound cavity modes can be realized in dielectric structures other than 3d photonic crystals. For a microcavity consisting of crossed anisotropic layers, we derive the cavity resonance frequencies, and spontaneous emission rates. For a dielectric structure with dissipative loss and central layer with gain, the beta factor of direct spontaneous emission into a cavity mode and the laser threshold is calculated.

  13. Scheme for Generation of Entanglement among Bimodal Cavities

    Institute of Scientific and Technical Information of China (English)

    SONG Xin-Guo; FENG Xun-Li

    2004-01-01

    @@ We present a scheme for generation of an entangled state in many spatially separated bimodal cavity modes via cavity quantum electrodynamics. A V-type three-level atom, initially prepared in a coherent superposition of its excited states, successively passes through both the bimodal cavities. If the atom is measured in its ground state after leaving the last cavity, an entangled state of many cavity modes can be generated. The conditions to generate the maximally entangled state with unity probability are worked out.

  14. Indirect Coupling between Two Cavity Photon Systems via Ferromagnetic Resonance

    CERN Document Server

    Hyde, Paul; Harder, Michael; Match, Christophe; Hu, Can-Ming

    2016-01-01

    We experimentally realize indirect coupling between two cavity modes via strong coupling with the ferromagnetic resonance in Yttrium Iron Garnet (YIG). We find that some indirectly coupled modes of our system can have a higher microwave transmission than the individual uncoupled modes. Using a coupled harmonic oscillator model, the influence of the oscillation phase difference between the two cavity modes on the nature of the indirect coupling is revealed. These indirectly coupled microwave modes can be controlled using an external magnetic field or by tuning the cavity height. This work has potential for use in controllable optical devices and information processing technologies.

  15. Cavity QED on a nanofiber using a composite photonic crystal cavity

    CERN Document Server

    Yalla, Ramachandrarao; Nayak, Kali P; Hakuta, Kohzo

    2014-01-01

    We demonstrate cavity QED conditions in the Purcell regime for single quantum emitters on the surface of an optical nanofiber. The cavity is formed by combining an optical nanofiber and a nanofabricated grating to create a composite photonic crystal cavity. Using this technique, significant enhancement of the spontaneous emission rate into the nanofiber guided modes is observed for single quantum dots. Our results pave the way for enhanced on-fiber light-matter interfaces with clear applications to quantum networks.

  16. Cavity quantum electrodynamics on a nanofiber using a composite photonic crystal cavity.

    Science.gov (United States)

    Yalla, Ramachandrarao; Sadgrove, Mark; Nayak, Kali P; Hakuta, Kohzo

    2014-10-01

    We demonstrate cavity QED conditions in the Purcell regime for single quantum emitters on the surface of an optical nanofiber. The cavity is formed by combining an optical nanofiber and a nanofabricated grating to create a composite photonic crystal cavity. By using this technique, significant enhancement of the spontaneous emission rate into the nanofiber guided modes is observed for single quantum dots. Our results pave the way for enhanced on-fiber light-matter interfaces with clear applications to quantum networks.

  17. Cavities/Tooth Decay

    Science.gov (United States)

    Cavities/tooth decay Overview By Mayo Clinic Staff Cavities are permanently damaged areas in the hard surface of your teeth ... into tiny openings or holes. Cavities, also called tooth decay or caries, are caused by a combination of ...

  18. Efficient Scheme for the Generation of Atomic Schroedinger Cat States in an Optical Cavity

    Institute of Scientific and Technical Information of China (English)

    ZHENGShi-Biao; LINLi-Hua; JIANGYun-Kun

    2003-01-01

    An efficient scheme is proposed for the generation of atomic Schroedinger cat states in an optical cavity. In the scheme N three-level atoms are loaded in the optical cavity. Raman coupling of two ground states is achieved via a laser tield and the cavity mode. The cavity mode is always in the vacuum state and the atoms have no probability of being populated in the excited state. Thus, the scheme is insensitive to both the cavity decay and spontaneous emission.

  19. Efficient Scheme for the Generation of Atomic Schrodinger Cat States in an Optical Cavity

    Institute of Scientific and Technical Information of China (English)

    ZHENG Shi-Biao; LIN Li-Hua; JIANG Yun-Kun

    2003-01-01

    An efficient scheme is proposed for the generation of atomic Schrodinger cat states in an optical cavity. Inthe scheme N three-level atoms are loaded in the optical cavity. Raman coupling of two ground states is achieved via alaser field and the cavity mode. The cavity mode is always in the vacuum state and the atoms have no probability ofbeing populated in the excited state. Thus, the scheme is insensitive to both the cavity decay and spontaneous emission.

  20. Efficient generation of Bell-cat states in remote cavities

    Institute of Scientific and Technical Information of China (English)

    LI Xing; ZHANG Ying-Jie; XIA Yun-Jie

    2008-01-01

    In the context of cavity quantum electrodynamics (QED), a potential scheme is proposed to generate entangled coherentstates. The scheme includes twice interactions of two-level atoms with cavities. In the first interaction, two atoms are sentinto a microwave cavity with the large detuning respectively. And then the second interaction is that the two atoms enteranother microwave cavity and are driven by a resonant classical field meantime. When we choose the proper interactiontime and make measurement on the two atoms, the two microwave cavity mode fields are determinatively entangled. Inaddition, it is easy to generalize the scheme to multi-cavity and multi-atom.

  1. Injector Cavities Fabrication, Vertical Test Performance and Primary Cryomodule Design

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Haipeng [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Cheng, Guangfeng [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Clemens, William [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Davis, G [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Macha, Kurt [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Overton, Roland [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Spell, D. [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States)

    2015-09-01

    After the electromagnetic design and the mechanical design of a β=0.6, 2-cell elliptical SRF cavity, the cavity has been fabricated. Then both 2-cell and 7-cell cavities have been bench tuned to the target values of frequency, coupling external Q and field flatness. After buffer chemistry polishing (BCP) and high pressure rinses (HPR), Vertical 2K cavity test results have been satisfied the specifications and ready for the string assembly. We will report the cavity performance including Lorenz Force Detuning (LFD) and Higher Order Modes (HOM) damping data. Its integration with cavity tuners to the cryomodule design will be reported.

  2. Cavity design and linear analysis of 225 GHz frequency-quadrupling gyroklystron

    Institute of Scientific and Technical Information of China (English)

    Liu Di-Wei; Yuan Xue-Song; Yan Yang; Liu Sheng-Gang

    2009-01-01

    This paper considers the frequency-quadrupling three-cavity gyroklystrons with successive frequency-doubling in each cavity. The cavities of 225 GHz frequency-quadrupling gyroklystron are designed with the scattering matrices method and the possible operating mode are discussed. With the point-gap theory, the starting currents of the possible operating modes and the potential parasitic modes in the output cavity are calculated. The optimal operating mode is proposed under consideration of the mode competition and the power capacity of the cavity.

  3. Effective Scheme for Generating Cluster States in Cavity QED

    Institute of Scientific and Technical Information of China (English)

    WU Huai-Zhi; YANG Zhen-Biao; ZHENG Shi-Biao

    2007-01-01

    We propose a scheme to prepare many two-mode cavities into one-dimensional cluster states in the context of cavity QED. The left-circularly polarized state and right-circularly polarized state of the cavity are encoded as the logic zero and one of the qubits. In the scheme, the atomic spontaneous emission is suppressed, and the fidelity is unaffected by the cavity decay on the assumption that the detection efficiencies of all the photondetectors are 1.

  4. Heavy colored SUSY partners from deflected anomaly mediation

    CERN Document Server

    Wang, Fei; Yang, Jin Min; Zhang, Yang

    2015-01-01

    We propose a deflected anomaly mediation scenario from SUSY QCD which can lead to both positive and negative deflection parameters (there is a smooth transition between these two deflection parameter regions by adjusting certain couplings). Such a scenario can naturally give a SUSY spectrum in which all the colored sparticles are heavy while the sleptons are light. As a result, the discrepancy between the Brookheaven $g_\\mu-2$ experiment and LHC data can be reconciled in this scenario. We also find that the parameter space for explaining the $g_\\mu-2$ anomaly at $1\\sigma$ level can be fully covered by the future LUX-ZEPLIN 7.2 Ton experiment.

  5. 强耦合光机械腔中的简正模式分裂和冷却%Normal mode splitting and cooling in strong coupling optomechanical cavity

    Institute of Scientific and Technical Information of China (English)

    陈华俊; 米贤武

    2011-01-01

    研究由辐射压力与驱动Fabry-Perot光学腔相耦合而产生的腔光机械动力学行为.通过量子朗之万方程具体研究了机械振子的涨落光谱、机械阻尼与共振频移和基态冷却.随着输入激光功率的增加,振子的涨落光谱呈现简正模式分裂的现象,并且数值模拟结果和实验结果相符合.同时推导了有效机械阻尼和共振频移.红移边带导致了机械模的冷却,蓝移边带引起了机械模的放大.此外,引入一种近似机制来研究振子的基态冷却,并且考虑在解析边带机制下简正模式分裂对机械振子冷却的影响.最后,数值讨论了初始浴温度、输入激光功率和机械品质因数这三个因素对机械振子冷却的影响.%A model describing optomechanical dynamics via radiation-pressure coupling with a driven optical cavity is investigated by a linearized quantum Langevin equation.The spectrum of the oscillator presents normal mode splitting with the increase of the input laser power in strong coupling regime and our results are in good agreement with the experimental results.The effective mechanical damping and the resonance frequency shift are derived.The redshifted sideband leads to the cooling of the mechanical oscillator,and the blueshifted motional sideband results in amplification.Furthermore,an approximate mechanism is introduced to analyze the cooling of the mechanical oscillator.Since both the normal mode splitting and cooling require working in the resolved sideband regime,whether the normal mode splitting influences the cooling of the mirror is considered.Meanwhile,we give three key factors influencing the cooling of mechanical oscillator,these being initial bath temperature,input laser power and mechanical quality factor.

  6. Normal mode splitting and cooling induced by radiation pressure in strong coupling optomechanical cavity%辐射压力诱导强耦合光机械腔中的简正模式分裂和冷却

    Institute of Scientific and Technical Information of China (English)

    陈华俊; 米贤武

    2012-01-01

    A model describing optomechanical dynamics via radiation-pressure coupling with a driven optical cavity was investigated by a linearized quantum Langevin equation under resolved sideband regime.Both the movable mirror and output field present the normal mode splitting with increasing of the input laser power and the results approach the experiment very well.The effective mechanical damping and resonance frequency shift are derived.The redshift sideband leads to cooling of the mechanical oscillator and the blueshift motional sideband results in amplification.Furthermore,an approximation scheme is introduced to analyze cooling of the mechanical oscillator.Since both the normal mode splitting and cooling require working in the resolved sideband regime,whether the normal mode splitting influence cooling of the mirror is considered.Meanwhile,the key factors that dominate the ground state cooling are also discussed.%在解析边带机制下用量子郎之万方程研究一种由辐射压力与驱动Fabry-Perot光学腔相耦合而产生的光机械动力学行为.随着输入激光功率的增加,振子的涨落光谱呈现简正模式分裂的现象,并且结果和实验相符合.也推导了有效机械阻尼和共振频移.红移边带导致了机械模的冷却,蓝移边带引起了机械模的放大.此外,引入一种近似机制来研究振子的冷却.由于简正模式分裂和基态冷却都要求在解析边带机制下,这就需要考虑简正模式分裂是否会影响到振子的冷却.同时也讨论了操控基态冷却的关键因素.

  7. Simulations of directed energy comet deflection

    Science.gov (United States)

    Zhang, Qicheng; Lubin, Philip M.; Hughes, Gary B.

    2016-09-01

    Earth-crossing asteroids and comets pose a long-term hazard to life and property on Earth. Schemes to mitigate the impact threat have been studied extensively but tend to focus on asteroid diversion while neglecting the possibility of a comet threat. Such schemes often demand physically intercepting the target by spacecraft, a task feasible only for targets identified decades in advance in a restricted range of orbits. A threatening comet is unlikely to satisfy these criteria and so necessitates a fundamentally different approach for diversion. Comets are naturally perturbed from purely gravitational trajectories through solar heating of their surfaces which activates sublimation-driven jets. Artificial heating of a comet, such as by a high-powered laser array in Earth orbit, may supplement natural heating by the Sun to purposefully manipulate its path to avoid an impact. The effectiveness of any particular laser array for a given comet depends on the comet's heating response which varies dramatically depending on factors including nucleus size, orbit and dynamical history. These factors are incorporated into a numerical orbital model using established models of nongravitational perturbations to evaluate the effectiveness and feasibility of using high-powered laser arrays in Earth orbit or on the ground to deflect a variety of comets. Simulation results suggest that orbital arrays of 500m and 10GW operating for 10 min=d over 1 yr may be adequate for mitigating impacts by comets up to 500m in diameter. Continuously operating ground-based arrays of 100m and 10GW may be similarly effective when appropriately located.

  8. Quantization of Electromagnetic Fields in Cavities

    Science.gov (United States)

    Kakazu, Kiyotaka; Oshiro, Kazunori

    1996-01-01

    A quantization procedure for the electromagnetic field in a rectangular cavity with perfect conductor walls is presented, where a decomposition formula of the field plays an essential role. All vector mode functions are obtained by using the decomposition. After expanding the field in terms of the vector mode functions, we get the quantized electromagnetic Hamiltonian.

  9. Investigations of a Coherently Driven Semiconductor Optical Cavity QED System

    Science.gov (United States)

    2008-09-30

    wavelength range of interest, the wavelength blueshift be- tween room and low temperature is 17 nm. 2 PL measure- ments through the fiber taper are...from the cryostat and blueshifted through a digital etching process 50 and the steps are repeated. 1. Room temperature cavity mode spectroscopy Room...small cavity mode blueshift of 0.8 nm per cycle, and does not degrade the cavity Q for the devices studied Q=105 and the number of etch cycles in

  10. HOM Coupler Notch Filter Tuning for the European XFEL Cavities

    OpenAIRE

    Sulimov, Alexey

    2015-01-01

    The notch filter (NF) tuning prevents the extraction of fundamental mode (1.3 GHz) RF power through Higher Order Modes (HOM) couplers. The procedure of NF tuning was optimized at the beginning of serial European XFEL cavities production. It allows keeping the filter more stable against temperature and pressure changes during cavity cool down. Some statistics of NF condition during cavities and modules cold tests is presented.

  11. Challenges of deflecting an asteroid or comet nucleus with a nuclear burst

    Energy Technology Data Exchange (ETDEWEB)

    Bradley, Paul A [Los Alamos National Laboratory; Plesko, Cathy S [Los Alamos National Laboratory; Clement, Ryan R. C. [Los Alamos National Laboratory; Conlon, Le Ann M [Los Alamos National Laboratory; Weaver, Robert P [Los Alamos National Laboratory; Guzik, Joyce A [Los Alamos National Laboratory; Pritchett - Sheets, Lori A [Los Alamos National Laboratory; Huebner, Walter F [SWRI

    2009-01-01

    There are many natural disasters that humanity has to deal with over time. These include earthquakes, tsunamis, hurricanes, floods, asteroid strikes, and so on. Some of these disasters occur slowly enough that some advance warning is possible for affected areas. In this case, the response is to evacuate the affected area and deal wilh the damage later. The Katrina and Rita hurricane evacuations on the U.S. Gulf Coasl in 2005 demonstrated the chaos that can result from such a response. In contrast with other natural disasters, it is likely that an asteroid or comet nucleus on a collision course with Earth will be detected with enough warning time to possibly deflect it away. Thanks to Near-Earth Object (NED) surveys, people are working towards a goal of cataloging at least 90% of all near-Earth objects with diameters larger than {approx} 140 meters in the next fifteen years. The important question then, is how to mitigate the threat from an asteroid or comet nucleus found to be on a collision course with Earth. In this paper. we briefly review some possible deflection methods, describe their good and bad points, and then embark on a more detailed description of using nuclear munitions in a standoff mode to deflect the asteroid or comet nucleus before it can hit Earth.

  12. Dynamics and control of a solar collector system for near Earth object deflection *

    Institute of Scientific and Technical Information of China (English)

    Shen-Ping Gong; Jun-Feng Li; Yun-Feng Gao

    2011-01-01

    A solar collector system is a possible method using solar energy to deflect Earth-threatening near-Earth objects. We investigate the dynamics and control of a solar collector system including a main collector (MC) and secondary collector (SC).The MC is used to collect the sunlight to its focal point, where the SC is placed and directs the collected light to an asteroid. Both the relative position and attitude of the two collectors should be accurately controlled to achieve the desired optical path. First,the dynamical equation of the relative motion of the two collectors in the vicinity of the asteroid is modeled. Secondly, the nonlinear sliding-mode method is employed to design a control law to achieve the desired configuration of the two collectors. Finally,the deflection capability of this solar collector system is compared with those of the gravitational tractor and solar sail gravitational tractor. The results show that the solar collector is much more efficient with respect to deflection capability.

  13. Study of Tensile Properties and Deflection Temperature of Polypropylene/Subang Pineapple Leaf Fiber Composites

    Science.gov (United States)

    Hafizhah, R.; Juwono, A. L.; Roseno, S.

    2017-05-01

    The development of eco-friendly composites has been increasing in the past four decades because the requirement of eco-friendly materials has been increasing. Indonesia has a lot of natural fiber resources and, pineapple leaf fiber is one of those fibers. This study aimed to determine the influence of weight fraction of pineapple leaf fibers, that were grown at Subang, to the tensile properties and the deflection temperature of polypropylene/Subang pineapple leaf fiber composites. Pineapple leaf fibers were pretreated by alkalization, while polypropylene pellets, as the matrix, were extruded into sheets. Hot press method was used to fabricate the composites. The results of the tensile test and Heat Deflection Temperature (HDT) test showed that the composites that contained of 30 wt.% pineapple leaf fiber was the best composite. The values of tensile strength, modulus of elasticity and deflection temperature were (64.04 ± 3.91) MPa; (3.98 ± 0.55) GPa and (156.05 ± 1.77) °C respectively, in which increased 187.36%, 198.60%, 264.72% respectively from the pristine polypropylene. The results of the observation on the fracture surfaces showed that the failure modes were fiber breakage and matrix failure.

  14. Ferrite-filled cavities for compact planar resonators

    Science.gov (United States)

    Keatley, P. S.; Durrant, C. J.; Berry, S. J.; Sirotkin, E.; Hibbins, A. P.; Hicken, R. J.

    2014-01-01

    Sub-wavelength metallic planar cavities, closed at one end, have been constructed by wrapping aluminium foil around teflon or ferrite slabs. Finite cavity width perturbs the fundamental cavity mode frequency of ferrite-filled cavities due to different permeability inside and outside of the cavity, in contrast to teflon-filled cavities, while the cavity length required to achieve a specific resonance frequency is significantly reduced for a ferrite-filled cavity. Ferrite-filled cavities may be excited by an in-plane alternating magnetic field and may be advantageous for high-frequency (HF) and ultra HF tagging and radio frequency identification of metallic objects within security, manufacturing, and shipping environments.

  15. Geoid Height and Deflection of the Vertical Models

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Office of the National Geodetic Survey has produced a series of high-resolution gravimetric geoid models, hybrid geoid models, and associated deflection of the...

  16. Deflection measurements of LABAN canister sections in horizontal attitude

    Energy Technology Data Exchange (ETDEWEB)

    Wakeman, W.

    1985-01-08

    Deflection measurements made on the LABAN canister sections indicate that the apparent stiffness of its frames, with all the diagnostics experiments installed, is not significantly different from the stiffness of the bare frames.

  17. U.S. East-West Deflections (DEFLEC96)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This 2' surface deflection of the vertical grid for the conterminous United States is the DEFLEC96 model. The computationused about 1.8 million terrestrial and...

  18. U.S. North-South Deflections (DEFLEC96)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This 2' surface deflection of the vertical grid for the conterminous United States is the DEFLEC96 model. The computationused about 1.8 million terrestrial and...

  19. Hawaiian Islands North-South Deflections (DEFLEC96)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This 2' surface deflection of the vertical grid for the Principal Hawaiian Islands is the DEFLEC96 model. The computation used about 61,000 terrestrial and marine...

  20. Hawaiian Islands East-West Deflections (DEFLEC96)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This 2' surface deflection of the vertical grid for the Principal Hawaiian Islands is the DEFLEC96 model. The computation used about 61,000 terrestrial and marine...